Problem with radiobuttons

Hello people. I am currently having a little problem with radiobuttons.

I used Flash Mx's radiobutton component to create 5 instances of the radiobuttons. I then used actionscript to assign label names to each of the radiobuttons. Next, I used actionscript to select the default radiobutton as folllows:

Code:

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radiobutton1.setState(true);

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where radiobutton1 is the instancename of my radiobutton. Once I test the scene out, the radiobutton is selected by default, as planned. However, the problem arises when I try to select another radiobutton. By right, when I select another radiobutton, the default selected radiobutton should be unselected, but it is not, which means that both radiobuttons are now selected. I try to unselect one of the radiobuttons but to no avail. What is the problem, and what could I do? Any help would be much appreciated, thanks.