problem in custome validaion

Question

hi

my problem is, i want to validation two controls in custom validation

please any body tell me how i am perform this thing.

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my code in javascript is
<script language="javascript" type="text/javascript">
function validate_CheckInOutTime(source, arguments)
{
var check_in_hour = document.aspnetForm.<%=dpl_check_in_hour.ClientID%>;
var check_in_minute = document.aspnetForm.<%=dpl_check_in_minute.ClientID%>;



var zero = "0";
alert(check_in_minute.value);

if(check_in_hour == zero && check_in_minute == zero)
{
alert(zero.value);
arguments.IsValid = false;
return;
}
else
{
arguments.IsValid = true;
return;
}
document.aspnetForm.dpl_check_in_hour.focus();
}
</script>

but this does not validate