Autoadvance clearTimeout not working

I tried to use this code to set up a question that autoadvances either after 8 seconds or when a response is chosen. Unfortunately, the clearTimeout isn’t working. If a response is chosen, the following page will autoadvance when 8 seconds has elapsed.

Any help solving this problem would be much appreciated!!

Qualtrics.SurveyEngine.addOnload(function() {
this.hideNextButton();
var that = this;
var to = setTimeout(function(){
that.clickNextButton();
},8000);
that.questionclick = function(event,element){
if (element.type == 'radio') that.clickNextButton();
};
Qualtrics.SurveyEngine.addOnPageSubmit(function() {
clearTimeout(to);
});
});