Onclick event not working

<asp:ImageButton ID="Img1" ImageUrl='<%#Eval("ProductImage") %>' runat="server" Width="30px" Height="30px" OnClick="MakeImgMain" />

protected void MakeImgMain(object sender, EventArgs e)
        {
            string ID = ((ImageButton)sender).ID;
            string CLientID = ((ImageButton)sender).ClientID;
            string url = ((ImageButton)sender).ImageUrl;
            ChangeImageOnClick(url);
            UpdatePanel5.Update();
        }

        public void ChangeImageOnClick(string url)
        {
            string imageurl = url;
            Image selimg = ((Image)ProdDescDetails.Items[0].FindControl("Prodimage"));
           // selimg.ImageUrl = "";
            selimg.ImageUrl = imageurl;
        }