Webdriver unable to click x-grid3-row-checker

[suna...@gmail.com]

I am working on a application which has 3 menus with arrows. Clicking the arrows will pop-up a window. In this pop-up window, there are multiple check few boxes. Check a checkbox and close the popup. I am able to select a checkbox for the first menu popup window by using the index of x-grid3-row-checker. But for the next menu, I am unable to click the checkbox in a particular row.  I'm trying to click the element using the xpath generated through Firepath, but with no luck.  <div class="x-grid3-cell-inner x-grid3-col-checker" unselectable="on">

<div class="x-grid3-row-checker"/> </div>. Can anyone please help me. Thanks in advance.

Thanks,
SuNan