SAP Message /ISDFPS/SYNC015 - Error reading RFC destination &1

Diagnosis
The RFC destination for the partner system could not be found.
Possible cause: an entry is missing in table /ISDFPS/ALE_SYS.

Procedure
In table /ISDFPS/ALE_SYS, the RFCDEST column must contain theRFC destination for the partner system (see SM59).