I'm trying to check/uncheck a checkbox using jQuery 1.12. This is my code:

```js
$(document).ready(function() {
  $('#btn-agree').click(function() {
    $('#checkbox-3').prop('checked', true);
  });
  $('#btn-notagree').click(function() {
    $('#checkbox-3').prop('checked', false);
  });
});
```

```html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.1/jquery.min.js"></script>
<input type="checkbox" name="agreement" id="checkbox-3" />
<button id="btn-agree">I Agree</button>
<button id="btn-notagree">Cancel</button>
```

When I click `btn-agree`, the function doesn't return any errors, but the checkbox is not checked. `console.log($('#checkbox-3').prop('checked');` show `true`

Can anyone point out what's wrong in my code?

**edit**
I believe the problem comes from somewhere else in my project. please feel free to delete this question.