Diagnosis
Distributor has reported internal partner as &SYST-MSGV1& which is notfound in the system. Distributor's partner is reported as &SYST-MSGV2&and there is no mapping for this in the external to internal partnermapping (transaction /SAPHT/DRM_C10) for tracking partner &SYST-MSGV3&.

Procedure
Create an internal partner (customer master) which will get updated inthe external to internal partner mapping for tracking partnerSyst-msgv3 and external partner syst-msgv2. the newly createdinternal partner will also be updated in staging records withDistributor's partner as &SYST-MSGV2&, internal partner asSyst-msgv1 and tracking partner as syst-msgv3.
OR
Search for existing internal partners (customer master) based onaddress. The selected internal partner will get updated in theexternal to internal partner mapping for tracking partner &SYST-MSGV3&and external partner &SYST-MSGV2&. The newly created internal partnerwill also be updated in staging records with Distributor's partner asSyst-msgv2, internal partner as syst-msgv1 and tracking partner asSyst-msgv3.