Table: Selecting radio button deactivates button action. Why?

[Stefan Bley]

I've got a table with the first column filled with radio buttons to make rows selectable.
Next to the table there is a button associated to a handler method.

When I click the button the action handler is invoked as expected.
However, if I select a table row by clicking the row's radio button and then click on the button the handler method is not invoked anymore! Why is that?!

Regards, Stefan