have you implement custom transaction logic on server side?
You need to implement OnUpdateDataBeginTransaction / OnUpdateDataCommitTransaction / OnUpdateDataRollBackTransaction and return false for aUseDefaultTransactionLogic when there events are fired.
your handlers for these events should be set in StartTr and unset in CommitTr/RollBackTr.
see also this thread - Transaction control over Multple Server Side TDAMemDataTables , it has similar problem.