Let me try
I assumed your table is called "Customer" that have field called "CustTown"
Create two queries, 1st is counted query, and 2nd is select query, like this:
1st QUERY
1. Create query of your table in design view
2. Enable Total Query (click icon "Sigma" on toolbar)
3. Insert field that you consider to be a group...twice, example:
Insert CustTown in column 1 and in column 2
4a. Make sure, on column 1, row Total shows Group By
4b. Make sure, on column 2, row Total shows Count
5. Save the query to "qrCountCust"
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2nd QUERY
1. Create query design view
2. Insert your tabel "Customer" and query "qrCountCust" above as source.
3. Create relational from table Customer into qrCountCust on CustTown (drag fieldname CustTown from table Customer onto CustTown in qrCountCust)
4. Insert all field you want to show in report from table Customer
5. Insert field 'CountOfCustTown' from query qrCountCust
6. On row 'Criteria', column 'CountofCustTown', write this ">1" (without quotes)
7. Run this query.. Is all records show number greater than 1 on column 'CountOfCustTown'? If the answer is yes.. your query is successfull and ready to be a report source, else, read step-by-step my tip above.
8. Save this query to "qrReportCust"
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Now create your report, using wizard and point to this 'qrReportCust' as report data source.
Maybe HELP
PS: If you need more explanation, mail me and attach a sample database to me.
tertib@infomedia.web.id