SAP Message 5Z451 - The reference personnel number &1 has an invalid format

Diagnosis
The reference personnel number is stored on the database as a12-character field. The first 8 characters of the reference personnelnumber must be digits and the last 4 characters must be blanks. Thereference personnel number can only be linked to a personnel number inthe system if this is the case.
The last 4 characters of the reference personnel number &V1& are &V2&as well as blanks.