Does anyone know what code is being used to change the source? Is the OP trying ot use a different field in the source query, or something else?
One way to do it would be to have a completely different source query, with the same field names, rather than change the source.
setting me.recordsource = "different query" will work in the open event.
I use this in reports to produce the same report, but with a slightly different query.
eg.
-select delivered dates, or invoiced dates
-select one branch or all branches