Something about the SF controls I need to know about?
I would have to look at your logic in the class, but there is nothing tricky about the SF buttons. In fact, if you look at the Object Browser, you will see that it inherits off of the System.WIndows.Forms.Button. The only additional logic is localization and data binding which would not affect this logic.
If you are running VB.NET, make sure that the method of the button has a Handles associated with the method. Also, since you are calling the ShowDialog method you can also close the form by setting the DialogResult (also standard .NET).
DialogResult = OK
Do you have the same results when you call the DialogResult? If you don't find the problem please post the logic of the button (including the handler) so that I can see what the logic looks like. Thanks. 