Hello,
In CRM under transcation SMW01, open the BDoc that was created for the BP (by mentioning the BDoc message type or date or say last one hour etc) and then choose a particular BDoc and then
click on Errors/Receivers icon. You might get some details about the Idoc that was generated for the destination (ISU in this case).
Another option is to open transaction WE05 or WE19 to check the Idoc by mentioning the appropriate selection criteria.
Hope this helps!
Best Regards,
Shanthala.