email form help!!!

my error message in flash ide:

1061: Call to a possibly undefined method indexOf through a reference with static type flash.text:TextField.

my flash code:

submit_btn.addEventListener(MouseEvent.CLICK, sendData);



function sendData(evtObj:MouseEvent): void {

if (!email_txt.length || email_txt.indexOf("@") == -1 || email_txt.indexOf(".") == -1) {

results.text = "Please check your e-mail address.";

} else if (!message_txt.length) {

results.text = "Please enter your comments.";

} else if (!name_txt.length) {

results.text = "Please enter your name.";

} else {

//loadVariablesNum ("http://yoursite.com/mailform.php", 0, "GET");

trace(name_txt.text);
trace(email_txt.text);
trace(message_txt.text);

results.text = "Sending Data...";

}

}