An internal error occurred while calling the {api_name} API. (WIS
30270)
Cause
Information about the document or the data source is invalid or not available.
Action
Your administrator can trace the problem that caused the error by activating the tracking and verifying
the trace associated with the API.
This is from the Error Message Explained 4.0 witch is a sap official document.
that means the error is a general error whenever there is a "internal error".
u have to trace the error for further information .
