Hi Expert
I am seeing a strange issue in SAP. We are receiving an inbound idoc from external system to post the goods receipt against a PO.
Every time an idoc is going in error with message `EDI: Field OUTMOD in control record with value is invalid`. As per the F1 help for field `OUTMOD` of control record, this field should be blank for an inbound idoc. Now the issue is why system is giving this error message for an inbound idoc?
Another strange thing is, when I reprocess this idoc using tcode BD87 it gets processed and GR is posted but if same idoc with exactly same data comes from an external system goes in error with above error message 
Can anyone help me to understand, does system calls different UE/include/Programm when idoc is directly received from external system (Please note that we are not using XI/PI) compared to when idoc is reprocessed using BD87
Any hint on this issue will be highly appriciated.
Thanks in advance.