Problems with Nulls and SQL UDT's

I created a UDT in C# that is working fine except when I request rows where the type is null.

If I use SELECT Film.ToString() FROM ImageData it works fine, or any property they return Null as expected

but if I use SELECT Film FROM ImageData it produces the error below

An error occurred while executing batch. Error message is: Data is Null. This method or property cannot be called on Null values.

I looked through all the examples in C# and my code matches the pattern for nulls exactly. Can anyone shead some light on what attribute I may have to add or method I should override which is not documented.

This was a bug. Please see http://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=125552

Cheers,