function check_three_checked()
{
	var tform = document.forms["thisform"]
	var c = 0;
	
	for (i = 0; i < tform.elements.length; i++)
  {
		if (tform.elements[i].className == "pledge")
    {
			if (tform.elements[i].checked)
			{
				c++;
			}
		}
	}
	
	if(c == 3)
	{
		document.getElementById('msg').style.visibility = "hidden";
		tform.submitbtn.disabled = false;
	}else{
		tform.submitbtn.disabled = true;
		document.getElementById('msg').style.visibility = "visible";
	}
}