Way To Hide Subreports Based On Item Existing In A Data Set.

My current report has around 40 subreports corresponding to tests executed by the user. There is a different sub report for each of the tests executed. I first developed the report by just putting the subreports directly on the main report. The problem is if some of my tests are not executed by the user I would like the subreports to not appear in the report.

I have tried doing this two different ways. First I tried creating a table and attaching that table to a dataset that I created that returns all the tests that were executed by the user. I then set up a filter that specified that the name for a specific subreport had to equal the test name. I then dropped the sub report for that particular test into the table. The idea is there would only be one row when data is available and no rows when no data is available so the subreport would not appear. When the data is available the subreport appears great. When it is not available and there is no item in the dataset for that test I get an error from SQL that states there was an internal reporting error and to check the SQL server log for more information. I know my table is set up correctly because when I replace the subreport with text the text will appear only if data is available for that test and the text does not appear if no data is available. I get no errors until I add the subreport and remove the data from the database so the filter does not return any items. Is there a reason why I would be getting this error? I am still pretty green using reporting services so I do not even understand how to get the log from the server to determine why this error is occuring.

Secondly I have tried to use an expression to hide the subreport using the visibility tab for the report. I was able to get this to work by creating a dataset that returns 1 if a specific test has been executed and no rows if not. I then created an expression that would return true if the dataset returned 1. This worked okay in hiding my subreport but I would then have to create 40 datasets, one for each test. Is there anyway to write an expression that would return true if a dataset contained a row with a specific test name? I have not been able to figure this out.

Can someone either help me fix the problem I am having with the table approach or write an expression that would work in the visibility setting for each sub report that did not require 40 datasets? Or is there another approach that I am not even thinking of that might work?

Thanks so much,
Josh