[RESOLVED] [02/03] Using the Controls Collection of a groupbox?

[Half]

Hi all, I am trying to uncheck the currently checked radiobutton in a groupbox with 6 radiobuttons. I have this:

Dim RB As RadioButton
        For Each RB In GroupBox4.Controls
            RB.Checked = False
        Next

I get "Specified cast is not valid" in line "For Each RB In GroupBox4.Controls". What am I doing wrong, the editor isn't showing any errors.