I have a report with 5 paramters, 2 are required (dates), 3 are not. For the 3 that are not, all are set to Allow NULL value and the dataset behind each one has a UNION Select NULL, '<Select a Value>'. When I preview the report, I select my dates and click View Report. Works perfectly. When I access the report from the webpage, I do the same exact thing...select my dates and click View Report. I then get an error message stating that 'The parameter cannot be blank.' It's referring to the last of the 5 parameters (one that is not required). I then have to actually select the <Select a Value> item and then click View Report to get the report to generate. 1. This does not happen when I preview in Visual Studio! and 2. It only does it for the 5th parameter --> parameters 3 & 4 are setup the same but it doesn't bark about them. So far, I've deleted the parameter and added it back, rebuilt & redeployed, but with no luck. Anyone have a clue as to why I'm getting this message at all since it is setup to Allow NULL and why does it only happen on the webpage and not in Preview mode? Thanks.