This happened because you have a sort on another page that has the same recordset name. Since the sort is saved in the session and the recordsets are the same it tries to retrieve the sort, but this page uses different tables and doesn't have the same column names.
The solution is to use unique recordset names when using search or sort server behaviors so that old search and sort values aren't re-used. I've updated the recordset from $rsORDERS to $rsDELORDERS so that it won't use search and sort values from other pages that use $rsORDERS.
