We recently upgraded our application from 11g to OBIEE12c. In 11g. We had implemented cache purge using DDR as shown in the screen shot below. Here "ODBC_pool" was a connection pool defined in RD, it was using default system DSN "AnalyticsWeb".

The above setup was working fine in 11g, but when we migrated to 12, the above DDR stopped working and gives error

Any idea what has changed in 12c which is causing this issue.
Thanks,
Deepali