Hi,
I tried the execution of a simple transformation in a Pentaho Server and in Carte same server, same repos, pentaho server running on xxxx port, carte running on yyyy port.
In Carte all was ok, in Pentaho server no! This the log:

2017-01-27 17:03:14,793 INFO [org.pentaho.di] 2017/01/27 17:03:14 - PurRepository - Creating repository meta store interface
2017-01-27 17:03:14,795 INFO [org.pentaho.di] 2017/01/27 17:03:14 - PurRepository - Connected to the enterprise repository
2017-01-27 17:03:14,796 INFO [org.pentaho.di] 2017/01/27 17:03:14 - PurRepository - Creating repository meta store interface
2017-01-27 17:03:14,797 INFO [org.pentaho.di] 2017/01/27 17:03:14 - PurRepository - Connected to the enterprise repository
2017-01-27 17:22:10,432 INFO [org.pentaho.di] 2017/01/27 17:22:10 - General - I couldn't find the repository with name 'xxx.xxx'
2017-01-27 17:22:10,444 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation is pre-loaded.
2017-01-27 17:22:10,444 DEBUG [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - nr of steps to run : 4 , nr of hops : 3
2017-01-27 17:22:10,445 INFO [org.pentaho.di] 2017/01/27 17:22:10 - PurRepository - Creating repository meta store interface
2017-01-27 17:22:10,454 INFO [org.pentaho.di] 2017/01/27 17:22:10 - PurRepository - Connected to the enterprise repository
2017-01-27 17:22:10,503 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Dispatching started for transformation [tr.test_append]
2017-01-27 17:22:10,503 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Safe mode is enabled for this transformation
2017-01-27 17:22:10,503 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - This is not a replay transformation
2017-01-27 17:22:10,503 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - I found 4 different steps to launch.
2017-01-27 17:22:10,503 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocating rowsets...
2017-01-27 17:22:10,503 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocating rowsets for step 0 --> Append streams
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - prevcopies = 1, nextcopies=1
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation allocated new rowset [Append streams.0 - Dummy (d
o nothing).0]
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocated 1 rowsets for step 0 --> Append streams
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocating rowsets for step 1 --> Dummy (do nothing)
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocated 1 rowsets for step 1 --> Dummy (do nothing)
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocating rowsets for step 2 --> Data Grid 1
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - prevcopies = 1, nextcopies=1
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation allocated new rowset [Data Grid 1.0 - Append streams.0]
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocated 2 rowsets for step 2 --> Data Grid 1
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocating rowsets for step 3 --> Data Grid 2
2017-01-27 17:22:10,504 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - prevcopies = 1, nextcopies=1
2017-01-27 17:22:10,505 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation allocated new rowset [Data Grid 2.0 - Append streams.0]
2017-01-27 17:22:10,505 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocated 3 rowsets for step 3 --> Data Grid 2
2017-01-27 17:22:10,505 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Allocating Steps & StepData...
2017-01-27 17:22:10,505 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation is about to allocate step [Append streams] of type [Append]
2017-01-27 17:22:10,505 DEBUG [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Step has nrcopies=1
2017-01-27 17:22:10,505 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Append streams.0 - distribution activated
2017-01-27 17:22:10,505 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Append streams.0 - Starting allocation of buffers & new threads...

2017-01-27 17:22:10,506 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Dummy (do nothing).0 - Finished dispatching
2017-01-27 17:22:10,507 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation has allocated a new step: [Dummy (do nothing)].0
2017-01-27 17:22:10,507 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation is about to allocate step [Data Grid 1] of type [DataGrid]
2017-01-27 17:22:10,507 DEBUG [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Step has nrcopies=1
2017-01-27 17:22:10,510 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - distribution activated
2017-01-27 17:22:10,510 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - Starting allocation of buffers & new threads...
2017-01-27 17:22:10,510 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - Step info: nrinput=0 nroutput=1
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - output rel. is 1:1
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - Found output rowset [Data Grid 1.0 - Append streams.0]
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - Finished dispatching
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation has allocated a new step: [Data Grid 1].0
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation is about to allocate step [Data Grid 2] of type [DataGrid]
2017-01-27 17:22:10,511 DEBUG [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Step has nrcopies=1
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - distribution activated
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - Starting allocation of buffers & new threads...
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - Step info: nrinput=0 nroutput=1
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - output rel. is 1:1
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - Found output rowset [Data Grid 2.0 - Append streams.0]
2017-01-27 17:22:10,511 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - Finished dispatching
2017-01-27 17:22:10,512 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Transformation has allocated a new step: [Data Grid 2].0
2017-01-27 17:22:10,512 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - This transformation can be replayed with replay date: 2017/01/27 17:22:10
2017-01-27 17:22:10,512 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Initialising 4 steps...
2017-01-27 17:22:10,513 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Append streams.0 - Released server socket on port 0
2017-01-27 17:22:10,513 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 1.0 - Released server socket on port 0
2017-01-27 17:22:10,514 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Data Grid 2.0 - Released server socket on port 0
2017-01-27 17:22:10,514 ERROR [org.pentaho.di] 2017/01/27 17:22:10 - Append streams.0 - ERROR (version 7.0.0.0-25, build 1 from 2016-11-05 15.35.36 by buildguy) : Both head and tail step need to be supplied.
2017-01-27 17:22:10,514 INFO [org.pentaho.di] 2017/01/27 17:22:10 - Dummy (do nothing).0 - Released server socket on port 0
2017-01-27 17:22:10,514 ERROR [org.pentaho.di] 2017/01/27 17:22:10 - Append streams.0 - ERROR (version 7.0.0.0-25, build 1 from 2016-11-05 15.35.36 by buildguy) : Error initializing step [Append streams]
2017-01-27 17:22:10,514 ERROR [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - ERROR (version 7.0.0.0-25, build 1 from 2016-11-05 15.35.36 by buildguy) : Step [Append streams.0] failed to initialize!
2017-01-27 17:22:10,514 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Step [Dummy (do nothing).0] initialized flawlessly.
2017-01-27 17:22:10,514 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Step [Data Grid 1.0] initialized flawlessly.
2017-01-27 17:22:10,514 INFO [org.pentaho.di] 2017/01/27 17:22:10 - tr.test_append - Step [Data Grid 2.0] initialized flawlessly.
...

Please look the transformation in attachmenttest_append.ktr

Maybe a configuration of pentaho server? Some lib missing? Carte is running inside the pentaho server installation...
Please help, thanks,
Davide