An error while performing operation 'sqlPrepareWithOptions' status='-126

[marsh06usn]

I am trying to do a Union between three queries but keep receiving the An error occurred while performing operation 'sqlPrepareWithOptions' status='-126'.  I am calculating week number by the function week(date) in each of the three queries.  One of the queries seems to be a different type of date than the other two, however, in my mind the function week() should return the same data type.  Nevertheless, I still tried to cast the data items to first integer, then string (using varchar(10)) and numeric.  I still receive the same error.  What is interesting is that numeric doesn't work for one of the data items.

Anyone come across this?  Any advice?