Validating number entries

On my Web page called [b]index.cfm[/b] I cant seem to get my Number validation working. Is there anything wrong with the below attempt??

[code]
<script>
function reqNum()
{
if (isNaN(document.updateproj.cust_id.value))
{
alert(“Enter number for cust id onlyn”);
return false;
}
else if(isNaN(document.updateproj.proj_id.value))
{
alert(“Enter number for proj id onlyn”);
return false;
}

}
</script>

<cfform action=”projecthere.cfm” method=”POST” enablecab=”No” name=”updateproj” onSubmit=”return reqNum();”>
<cfinput type=”text” name=”cust_id” value=”” />
<cfinput type=”text” name=”proj_id” value=”” />

[/code]

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