Question: What I want is when checkbox1 is selected both checkbox labelled 1 will get selected and background will be removed

[here is the fiddle](http://jsfiddle.net/rigids/D2vCf/)

for eg if i select checkbox1 it should select both checkbox labelled checkbox1

Answer: 
The problem is that searching for ID $("#somethin") is not possible to select more than one element. IF you search for class, then your example works.. well, with [some minor changes](http://jsfiddle.net/D2vCf/11/) :)

```
$(document).ready(function() {
  $('input[type=checkbox]').change(function(){
        var pos;
        pos = this.id;

       // global hook - unblock UI when ajax request completes
        $(document).ajaxStop($.unblockUI);

        if($(this).prop("checked")) {
            $("."+pos).parent().removeClass("highlight");
            $("."+pos).prop('checked', true)

            //ajax to add uni
        } else {
            //ajax to remove uni
            $("."+pos).parent().addClass("highlight");
            $("."+pos).prop('checked', false)

        }
    });

 });

```
You can't have multiple DOM elements with the same id.

See [this fiddle](http://jsfiddle.net/PL6MW/1/) for a working example, but it's not as generic as you may need.