SSRS deselecting some values from multi-select paramter

Question

I have a report with a multi-select parameter. The first time you run the report, everything works fine.

My issue is, if you choose the value Select All for AssetTypes and run the report - all good. If you change one of the other parameters values (there are 4 others) and run the report again the AssetTypes list of values changes. The Select All option is deselected and 2 other seemingly random values are also deselected??

I am printing the value count on the report as debugging.

=CStr(Parameters!AssetTypes.Count) + "-" + CStr(CountRows("ParamAssetTypes")) 

The first time you run it - the values are 59 and 59 The second time you run (I don't even look at the AssetTypes list - I just run it again) the values are 56 and 59.

I am running VS2010 and SQL 2008

Has anyone encountered this before?

Answer 1

I suspect you are feeding duplicated values into the Parameter's Available Values / Value Field. SSRS gets very confused by this.

I would fix this will a GROUP BY or similar technique in the source Dataset.