I think I found a bug in Csla 4.5.501.
You can recreate it by creating a simple editable business object and a business rule where the rule ctor throws an exception.
In my case, I was throwing an ArgumentException if one of the propertyInfo.Type != typeof(string) as the rule only works against string properties.
The end result was that Csla from the SimpleDataPortal was throwing a NullReferenceException which was not the exception actually thrown by the ctor prior to the call getting to my DP_F method.. I'm calling this a bug because it took me a few hours to figure out what was going on. I would have expected to see my ArgumentException somewhere, not a NRE from an anonymous' classes MoveNext method. :-)
