Hi Dave,

Error trapping in UDF is very limited.  You're best approach is validating the input before use.  In this case, the ISDATE function would do the trick. 

There's also the...

In addition to locking as a likely cause, another reason for the difference can be I/O times.  If there is a major difference in the amount of framgmentation between the...

I've found that DB2 (on a 400) is case sensitive in some places.  In particular, I suggest that you capitolize the library.schema.table name, which you have in lower case. 

Doing what you want isn't possible in a UDF.  UDF's don't allow execution of dynamic SQL.  The results set returned by the UDF must be declared when the UDF is...

There's a function that will do what you want at this link:

http://www.novicksoftware.com/UDFofWeek/Vol2/T-SQL-UDF-Vol-2-Num-14-udf_DT_NthDayInMon.htm

Regards,

Andy