refreshing recordset for data control

I have 2 forms, the first has a listbox and a selection of tests. When the user selects a test and clicks begin I use DAO to locate its asociated tablename from a table in a A2k database.

The second form contains the tests. I don't seem to be able to change the recordsourse with the tablename string from the first form. I have tried all sorts of ways. Here is a sample of code I have tried on form1.
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form2.data1.recordsource = myTablestr
form2.data1.refresh
form2.show
unload me
set form1 = nothing
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I find that the recordsource does not change

Help appreciated