Message SAP WS408 - An internal error occurred

Diagnosis
An internal error occurred during reading of configuration data.

System Response
The function was terminated.

Procedure
INCLUDE ISR_VERWALTUNG

Procedure for System Administration
Check the entries in Customizing table TMFK. Contact SAP if necessary.
The error occurred in sub-program TMFK_select_check in in functiongroup wlf_invoice_test_docs. Structures ts_tmfk and ts_lfart are bothempty.