Try this
<script type="text/javascript">
function txtChange(chkCheckbox) {
var td = chkCheckbox.offsetParent;
var inputs = td.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
if (inputs[i].type == 'checkbox') {
inputs[i].checked = true;
break;
}
}
}
</script>
onchange="txtChange(this);