This happens when you have Referential Integrity setup in your database and you tried to create an index (IDX) in one of the tables. You usually create the stand-alone IDX to create the parent-child relationship or you were trying to create a temporary index to 'effect' a sort on a column from one of the related tables.

I haven't tried this but this may work.
1. Use the existing CDX instead; just be sure to delete the tag afterwards. This way RI can still enforce the rules since the CDX is still open. Creating stand-alone IDX closes the CDX, I think.
2. Build the additional sort on top of the relation keys
Parent.ID = Child.ID + Child.AdditionalSortColumn

HTH.

>I have a table with unique job numbers. I have two other tables that hold the scope of work for these job numbers. Thes tables represent departments with fields to hold dates, hours and resources. I have one form that displays the job number and two grids each representing departments displaying the schedule of work. I have these grids linked to the main table. When I scroll the main table I get an error that "Target Table is already engaged in a relation. Is there another way to do this? Or can I fix what I have an avoid the error?