Gridview is not set at first page during binding

I have dropdown list on my page. When I click on submit button, gridview is filled based on the choice in the dropdown list. It also contains pagging. Now when 开发者_JAVA技巧I move on page two and then change dropdown list value and again fill the grid, it fill perfectly but shows from the previous page index and not from the first page. I trid using "Gridveiw.PageIndex=0" but still its not working. What might be the reason behind this??

first set Gridveiw.PageIndex = 0; like you are doing and then bind the grid.