asp.net checkbox onclick event is not firing

I have a webpage contains drop down and check box, after selecting the value in drop down the focus is next set to check box. when try to select the check box click event is not firing. click anywhere else on the page then am able to select the check box and this is happening only in I.E.-11 version. Why cant we do select the check box when the focus is set on it ? Any solutions or work around for this issue.?

Thanks in advance, Shilpa