Need help please...new to JS

On Form submission, I am trying to pass a variable (var radioValue, which is the RadioButton selection) as Opt Label in the _gaq.push event tracker (google analytics)as follows

onclick="_gaq.push(['_trackEvent', 'Visitor', 'Submit', radioValue]);"

However radioValue value is not getting passed

Code snippets are attached below. Not sure whether the problem is in the JS function or whether i am calling the var incorrectly in the _gaq.push script...Thank you

The radioValue is captured in the overall form validation function as below.

Hari
-------------------------------------------------------------
(in HTML head)

/////other overall form functions
var radio_choice = false;
for (counter = 0; counter < document.form.RadioGroup.length; counter++)
{
if (document.form.RadioGroup[counter].checked == true){
radio_choice = true;
radioValue=(document.form.RadioGroup[counter].value);
}

}

if (!radio_choice)
{
alert("Please select again.");
return (false);
}

/////other overall form functions

------------------------------------------------------------

RadioButton Input script (in HTML body)

<input name="RadioGroup" value="abc1" type="radio" />abc1</td><td>&nbsp;</td></tr>
<input name="RadioGroup" value="abc2" type="radio" />abc1</td><td>&nbsp;</td></tr>
<input name="RadioGroup" value="abc3" type="radio" />abc1</td><td>&nbsp;</td></tr>