Hello Alexander,
Sorry for the delay, I just debug it and find where the error may be raising in the following code:
In the FM BBP_REQREQ_TRANSFER, the following Function reads details and lock requirement request -->
CALLFUNCTION'BBP_REQREQ_GETDETAIL'
Then it fill a table for the req_line = reqlines
Then they compare the lines to set the transfer to one system, if the system is not the same of the backend one loaded it throws the error.
* start transfer for all items to be transfered in one system
SORT h_reqline BYclient reqno reqlline.
PERFORM transfer_items.
IFNOT backend_flag ISINITIAL.
CALLFUNCTION'DEQUEUE_REQREQ'
EXPORTING
reqno = longkey-reqno.
MESSAGE e231 WITH h_logsys RAISING backend_not_responding.
EXIT.
So, I thought the error might be a wrong customizing because system does not interpret the correct business system in the product read or in the previously called bbp_logical_system_get.
Please do a check in the next tips -->
1. Where does your products come from? Is the middleware working all ok?
2. Which number ranges do you have configured in for Shopping Carts and for Backend follow-on documents?
3. What system do you specify in the number range for follow-on documents?
4. What is the system configured in your BBP_BACKEND_DEST? Please provide detail on the entries.
Hope it helps,
Reward points if usefull.
SG