Hi Thomas,
This error may be occurring because the corresponding persons do not exist in CRM with the corresponding personnel numbers mentioned in the Bdocs errors.
These personnel numbers do not correspond to customers from R/3, but to employees which are assigned to R/3 customers via employee specific partner functions.
Now the HR specific employee master data should be synchronized between
R/3 and CRM first. In addition the HR integration must be active in your
system so data for these employees is not rejected.
You have information about it in the customizing documentation:
IMG: Customer Relationship Management > Master Data >
Business Partner > Integration Business Partner-Employee > Set Up Integration With HR.
Note 550055 contains the necessary information.
Regards,
Gervase