SAP Message 5M133 - There is no SE number for this SE key in t5m5n

Diagnosis
You have entered an employer key (SE key) for which the system isunable to find a valid entry in the table of employer keys.

System Response
The system rejects the entry, and requires a correct one.

Procedure
Check that the SE key was entered correctly. If necessary, you canmaintain the SE key in table T5M5N.