SAP Message RY171 - External transaction number &: Unable to read internal number &

Diagnosis
You wanted to export the transaction. However, the system was unable tofind it on the database.
The system determines an internal number for the transaction from theexternal number. It then uses this internal number to access thetransaction on the database. However, it could not find atransactionwith this internal number on the database.

Procedure
Inform your system administrator.

Procedure for System Administration
No valid internal transaction number was transferred to the functionmodule. Check the calls. If the call is part of a standard SAP routine,then contact SAP.