I am facing the following issue while trying to use an aggregate fact table:

2014-09-05 14:52:54,004 WARN [mondrian.rolap.aggmatcher.AggGen] Init: For fact table "fact_event_transaction", could not get column name for RolapStar.Column: Fact Count (78): count(null)

fact_count column does exist in the DB and is referenced in the schema as follows:

<AggFactCount column="fact_count">

If anyone has any idea regarding this issue, please respond.