How to count # of entries in Workflow Designer

So I have a situation where in my workflow I need to count the # of entries that meet a certain index criteria.  In my case, I'm counting the # of Packing Slips that have the same invoice # that meets the index value of the invoice (that triggers the workflow).  I'm trying to use an Arithmetic Expression with the following and it's not working.

COUNT (DW_INVOICE__= GV_Packing_List_Invoice_No) AND (DW_DOCUMENT_TYPE = 'Packing List')

DW_INVOICE = Invoice # of the document that triggered the workflow
GV_Packing_List_Invoice_No = GV that is capturing the Invoice # of the Packing Slip in an earlier step

Thanks!!

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Hi Daryl, 

I think your arithmetic expression is a fancy way to say "2". 
If you want to count the number of documents meeting your criteria inside the file cabinet, you need to look it up in the database in your "assign data" step, however, this only works if your expected result is 100 or less.
f you expect more than 100 entries, you may need to use a webservice which searches for the number of documents and returns the number of results or rethink if this is the only way to reach your goal.

Hope this helps. 

Greetings from Germany, 
Simon H. Hellmann
DocuWare System Consultant