Oracle EBS 12 and OTM integration issues-refnum not coming

Hi All-

We are approaching our CRP for Oracle R12 upgrade. We have found a serious issue where the order type refnum is not flowing in from Oracle R12 to OTM v 6.2. This works perfectly fine in our production instance of OTM 5.5 and Oracle EBS 11.5.10 integration.

I believe this should be part of standard integration and if this works with 11i and OTM integration in production then am not able to find out why this is not working in the Oracle R12 and OTM 6.0 integration. There is no customization involved in our integration.

Please provide some help in this matter.