You mentioned DP V7 and Mon V8....
Is DP V7 processing the files using Mon V7? The versions should match on the Server.
If the Model was built in Mon V8, and processing via DP V7 and Mon V7, are you sure none of the new functionality in Mon V8 was used? This would include any new functions.
Are you using the same Export File Type?
If you like, please give me a call: 978-441-2200 (ask for Dee)
Datawatch Tech Support