Select frame to jump to w/combo

Hello,

I would like to use a combobox to select an item then, after pushing a button, jump to the appropriate frame based on the selected item. Here is my code so far:

submit_btn.onRelease = function () {
var disLetter = bis_cbo.getSelectedIndex();
getDisLetter();
}

function getDisLetter(){
gotoAndStop(disLetter);

}

Thanks for your help!