ModalPopUp is displaying when gridview index change

Question

I have modal pop up and grid view when i changing gridview index modal popUp automatically populated

 protected void gvVouchers_PageIndexChanging(object sender, GridViewPageEventArgs e)

    {

        obj.LoadVouchers(ref gvVouchers);

        gvVouchers.PageIndex = e.NewPageIndex;

        

    }