>That's exactly the problem - ControlSource is calling a procname(table.field) and SetOrder is horking all over that. Problem is, it's always been like this and the current executable that our customers are using isn't failing on this. Most confusing.
>
>not to mention frustrating
>
May be that column is not supposed to be sortable. If you click / double click on the header in the current version of software, does it give the error?

If not, may be there is some flag to not sort by this column? Or does it still sort correctly? May be also there is a property of the column where the correct Tag is stored.