Please use following
function checkCheckBox(){
var chk = document.getElementById('<%=chkAgree.ClientID%>');
if (chk.checked == false)
{
alert('Please check the box to continue.');
return false;
}
else
return true;
}
Thanks,
Imdadhusen
Updates Note:-
I have removed parameter from function because now it is no more nedded!
function checkCheckBox()