Error Message while calling WORKDAYS_BETWEEN function

I am wondering what the meaning is of the following error message:

"could not read working days information from the table TFACS "HANADB".'TFACS" - ErrorLevel = 1.

I sometimes get this error message when I call WORKDAYS_BETWEEN function.  This is a JDBC error.  The SQL is joining to two schemas, one is Oracle and the other is hanadb.  The full message in the Jdbc trace in hana studio is:attached in the text file.

Do you think it is due to permissions issues?  Is it possible to look at the code for the workdays_between function to try and figure out what the

issue is?  It works fine sometimes, but throws the message other times depending on the input variables.