Hi Don,
yes, we are using sessions for the website (no cookies).
Looking at the history of this thread - shall I prepare a VS-project with our *.RPT for debugging that on your own?
It is no CR-migration-problem (update from CR-vXY), because it the same with a newly created RPT (with VS 2013). I guess (caution, dangerous) it has something to do with the 64 bit-environment.
Btw., IIS is the same web-environment, on DEV and on PROD. Might be interessing.
Greetings
C. Lo