Problems when sending dynamic data from Flash with Firefox

Hello, welcome to long subject line!

I’m having problems sending data from Flash using the send command when in Firefox. This is the code I’ve got right now:

myData = new LoadVars();
submit.onPress = function() {
    if (additionalcomm.text != "") {
        myData.testing = additionalcomm.text;
        myData.send("save.php", "_self", "POST");
        additionalcomm.text = "At least the button works.";

Technically, it works, but only in Internet Explorer. Any way to fix this problem?