Hi,

I had similar issue in SSRS 2008.

When i tried to retrieve parameters (Date/Time) with labels (nvarchar(7)) after click "View report" parameters values picked from dropdown were cleared.

I read couple of topics on forums, but finally found out solution myself. Parameters had to be passed as Text not as Date/Time.

However problem might be caused by something else because in other report Date/Time as type of parameters in similar scenario works well.