Report-Sub Report in Visual Studio 2005

Hi everybody,
I have a problem on connecting subreports with reports.
I create the sub report, bind data to it, and filter the
data (in the query) with something like Case_Id = @.ParamCaseID.
I create the parameter ParamCaseID in the subreport and then I go
to the primary report and set the property parameters of the subreport
to ParamCaseID and value to (=Fields!PrimaryCaseID.Value).
I run the application to see the report and although the report is
showing I get the error "Subreport could not be shown" in the
place where the subreport was supposed to appear.
What am I doing wrong ?
Any help would be useful .
Thanks in advance.
To answer by e-mail remove the "bog" from the e-mail.I use SQL Server 2005 Reporting Services of course.sql