There is something that does not seem quite right here. You say that you retrieve StartDate and EndDate, but your sample query only has two columns.

Your error message barfs about...

To find the permissions required for a specific catalog view or DMV, look up to the topic for the view in question in Books Online. There is usually a permissions...

To expand a little on Luis's answer, SQL Server has a strict data type-precedence which says that when two types meet, the type with lower precedence will be converted to...