I have a similar problem to:
I have set up the parameters in the subreport (these actually came across when I mapped to the stored procedure). They are visible, and the report runs fine when I view it in its own right. However, when I set it up as a subreport, (mapping the parameters from the parent to the subreport using those from the parameter list), the parameters don't carry to the subreport. I get the error:
Data Retrieval failed for Subreport
The parameters are the same for both reports (except for one additional one that I am linking from the parent dataset). They have the same names, and have been matched correctly. I tried entering values for the subreport parameters, and these aren't getting through.