Multiple Multiselect Listboxes

Hi, my problems are numerous!
I have a form with a number of multiselect listboxes. Their sources are individual tables such as YEARS, PARISHES, CLIENTS. The underlying data is stored in a separate table. I want users to be able to select none, one or some values from each listbox and run a report.
As simple listboxes with one selection permitted this worked fine. I know that my problem is in concantenating the values.

I have tried attaching some code to the OnClick function of a cmd button on the form. I found this code referred to a number of times here and have tried to adapt it but no luck. I have now reduced my form to one listbox to test stuff out- this is the code-

Dim frm As Form, ctl As Control
Dim varItem As Variant
Dim strSQL As String
Set frm = Form!testform
Set ctl = frm!lboparish
strSQL = "Select * from StJamesAgric where [Parish]="
For Each varItem In ctl.ItemsSelected
strSQL = strSQL & ctl.ItemData(varItem) & " OR [Parish]="
Next varItem

'Trim the end of strSQL
strSQL=left$(strSQL,len(strSQL)-300)

The first error I get is "can't find field 'testform'"

My form is called testform
The listbox is called lboparish
The table with all the data is called StJamesAgric

What am I doing wrong???? And also, if this code EVER works, do I need to repeat it for each listbox or do I insert refernces to each list box within just one subcommand?

Any help greatly appreciated.

Stella