I've setup a RadioButtonGroup with 5 options (values 0-4) on a user control.  The designer sets the Checked property of the option with the value of 0 to True.  I manually change the property back to False and save the file.  Everythings looks fine at this point, no options with a Checked property of True.  I close the user control designer in VS and then reopen it and the option with the value of 0 is "checked" again.

I want the user control to render with no option selected and if the BO is saved without the user making a selection I want a required field broken rule to be displayed.  Can I make the RadioButtonGroup do this?

Thanks Trent that works great but now I'm being tripped up by my BO the control is bound to.  The field in the database is a smallint that allows nulls.  When I configure the BO in the BO Mapper I customize the field to use a Null Type of Use Nullable Generic which is 0 for this datatype.  So when I perform a BO.Add the BO property for the field in question gets set to 0 which is the value of one of my options so it always displays with an option selected.

How should I setup the database field and BO Mapping so no option is selected on a BO.Add?  I need to use the values 0-4 for the option values since they are later used in summary calculations.

Just return an alternate value on NULL and set it to a -1 or something like that.  This way you do not have a collision of values and NULL.