Uncheck the checkbox list items on event in gridview

I have an image button as item template in all the rows of a gridview. A popup (with checkboxlist items, update and cancel button)will be displayed on clicking the image button. Say there are 4 rows in the gridview . For first row I click on the image button and I get a popup,  I select few items from checkboxlist and hit update button. The values get updated. Now the problem is when I click on the image button in the second row the checkbox selections made in the previous row is not cleared. How to get rid of this problem? ? For each row I want the checkbox selection to be unique. That is : For the first row whichever item I selected, should be checked still. But for the other rows it should not reflect. Hope you understand.

I believe the answer lies on how you populate your checkboxes. You might want to traverse on the checkboxes and uncheck them on the onclick event of the button. Could you post your code fragments?