How to make radio button trigger a list filter

Question

Hi,

I have a custom Web Part, which checks the group membership of the current user and sorts a list according to it. This works fine, when the user first logs on to the page. The Web Part also contain a radio button for each group on the site, so that the user can manually change the sorting of the list according to other groups than his own. This does not work, so I am wondering if I need some kind of annotation to on the connection, so that the list sorting is not only triggered when the page loads?