As DBIx::Simple is just a wrapper for DBI, the issue is very probably burried somewhere in the DBD, ODBC, or MS SQL. Unfortunately, I'm not familiar with those so I can't help you with that.

However, I should note that you should probably not call your DBIx::Simple object "$dbh", because people will expect that a variable named $dbh isa DBI handle. Also, you shouldn't use the DBIx::Simple object as a hash reference, contrary to DBI's object. That is, write $db->dbh instead of $dbh->{'dbh'}. This has nothing to do with the problem at hand, but changing your style will prevent mistakes later.