Issue accepting sub-report parameters using Command queries

Question

OK,
   I am using a query which accepts a linked parameter to create a sub-report. When I type the linked data straight into the query the data queries correctly. When I pass the same data through the parameter it doesn't pull any data. The query runs in SQL Management Studio so I know the data exists.
The query is:
select * from pmappedu Inner Join prmisccd on pmappedu.pmad_inst_cd = prmisccd.prms_code where  pmappedu.pmad_ssn='{?Pm-Command.pmaq_ssn}'
I can display the parameter value in the report and it's correct. All data types seem to match. I am not sure what else to do.
Sam

Answer 1

For some reason the sub-report would not accept the parameter passed from the main report in the Command feature so I got around it by taking out the where clause and using the Select Expert to do my where clause in the report itself. However, this seems very counterintuitive and not at all what I would expect for a SQL-based report. If I am understanding the process correctly, the SQL query is returning ALL data unfiltered and then filtering the report at run-time of the Crystal processes instead of with the SQL engine on the SQL server. This is actually pretty ridiculous because of the performance hit that we would take on say, a million records.
Sam