Customer and supplier association is required when you are transferring AGIS transactions to subledger application like Receivables and payables respectively.

Usually association would be created between two different legal entities. One LE is initiator and another LE is recipient.

Recipient LE name would be defined as Customer in Initiator LE and vice versa.

If you are not able to defined association for one LE, then issue with Intercompany Organization Set or may not have completed OU segment relating to that LE.

In udpate its not clear on what kind of error you are facing.

Also it is strongly adviced not to create discussions in Documents section as Documents section is reserved for sharing any documents/Information.

Documents section is not to post questions. Posting this query in Discussions would be more visible to community users.

Thanks,

RamPrasad