Sap Note 17847 - Error 06341, assign source of supply for pur. req.

Symptom:

When you manually assign a source of supply (ME57 ME56) or when you enter a source of supply in the detail screen of the item when creating (ME51) or changing (ME52), and the source of supply is a vendor, an error mesasge is issued:
06341 Info record for vendor xx and material yy does not exist.
This requirement is too strict.

Cause and prerequisites

The message is issued as an error message in standard.

Solution
Call transaction OMEO and change the category of message 06341 for version 00 from E (error) to W (warning).