ผมใช้ JavaScript ในการตรวจสอบค่าว่างของ Radio Button ของระบบข้อสอบ แต่มันไม่ทำงานครับ

function fncSubmit()
{
	if(document.form1.choice1.checked == false && document.form1.choice2.checked == false && document.form1.choice3.checked == false && document.form1.choice4.checked == false )
	{
		alert('Please Click Radio Option ');
		return false;
	}	
	document.form1.submit();
}
</script>

<form id="form1" name="form1" method="post" action="get-answer.php" onSubmit="JavaScript:return fncSubmit();">
  <h1>เลือกข้อที่ถูกต้อง</h1>
  <?php 
  $chNum=1;
  do { 
  
  ?>
    <p><?php echo $chNum; ?>) <?php echo $row_Recordset1['question']; ?></p>
    <p>
      <input type="radio" name="<?php echo $row_Recordset1['id']; ?>" id="choice1" value="ก" />
      ก. 
      <?php echo $row_Recordset1['choice1']; ?><br />
      <input type="radio" name="<?php echo $row_Recordset1['id']; ?>" id="choice2" value="ข" />
      ข. 
      <?php echo $row_Recordset1['choice2']; ?><br />
      <input type="radio" name="<?php echo $row_Recordset1['id']; ?>" id="choice3" value="ค" />
      ค. 
      <?php echo $row_Recordset1['choice3']; ?><br />
      <input type="radio" name="<?php echo $row_Recordset1['id']; ?>" id="choice4" value="ง" />
      ง. 
      <?php echo $row_Recordset1['choice4']; ?><br />
    </p>
    <?php 
	$chNum++;
	} while ($row_Recordset1 = mysql_fetch_assoc($Recordset1)); ?>
  <p>
    <input type="submit" name="btnSend" id="btnSend" value="Submit" />
  </p>
</form>