Modal Popup not working on gridview button click inside UpdatePanel

[shok]

I have a gridview inside UpdatePanel. One of the column in gridview is link which when clicked should display modal. The problem is the modal only gets displayed only once when the link is clicked, the next time when the link is clicked it just refreshes the page. The modal should be displayed everytime when the link inside the gridview is clicked.The solution given in this link is for jQuery. I am not using jQuery.Please help me to resolve this issue.