[AccessD] Use form field for IN statement in Where clause

In an Access 97 database 

I have a case type field in a reference table that may contain 1 to 11
values depending on what cases are used in a particular report 
   examples  report 1221 has this type  11
             report 1321 has these types 11,12,14,16,17


The field is placed into a hidden text field on a form called
[Forms]![FrmBicMoSel]![txtSelCriteria] 

The called query currently uses this field in the where statement this
way
 
(InStr([Forms]![FrmBicMoSel]![txtSelCriteria],[tlkpXrefDescID].[CaseType
])>0)) 

I would like to be able to use it with an IN statement 
[tlkpXrefDescID].[CaseType] in([Forms]![FrmBicMoSel]![txtSelCriteria])

But it does not like this - how can I get this to work - I think there
is a function but I can't seem to remember it right now. 

Thanks
******************************************************************
*Patricia O'Connor
*Associate Computer Programmer Analyst
*OTDA - BDMA
*(W) mailto:Patricia.O'Connor at otda.state.ny.us
*(w) mailto:aa1160 at otda.state.ny.us
****************************************************************** 
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