Hi Guys and Girls

I don't generally use javascipt as I am a .net developer but can anyone help me with the following page

<html>
<head>
<script language=javascript>
function validate(chk){
if (chk.checked == 1)
document.Form1.submit();
else
alert("Please ensure you accept the terms & conditions")
chk.focus();
}
</script>
</head>
<body>
<form ID="Form1">
<input type=checkbox name=chkterms ID="Checkbox1">Please Check Me
<p><input type=button value="check" onclick="return validate(chkterms);" ID="Button1" NAME="Button1">
</form>
</body>
</html>

if the box is not checked I get the alert text if I leave box unchecked I get the error document.Form1 is null or not an object

Can anyone help