This is my same problem! I have DNN 4.8.2 and Reports 5.0.0.
Here's the deal. SSRS and DNN were getting along great. I had 3 reports that I deployed via the Reports module within DNN, and they all displayed correctly. However, these reports didn't have any parameters.
Today, our developer updated the same 3 reports so that each has a grouping parameter. I redeployed the updated reports. Now you have a pick a paramter from the "Group By" dropdown list, and then click the "View Report" button. These 3 reports work fine when accessed through the SSRS web interface directly. However, when accessed through the reports module, nothing happens when you pick a parameter and click the "View Report" button.
What am I overlooking?
See Ya!
Van