Gridview Delete not working..

<asp:GridView ID="GridView1" runat="server" Width="40%" CellSpacing="2" AutoGenerateColumns="false" CellPadding="4" AllowPaging="true"
        PageSize="10" ForeColor="#333333"
        GridLines="Vertical" OnPageIndexChanging="GridView1_PageIndexChanging" DataKeyNames="Username"
       OnRowDeleting="GridView1_RowDeleting"  >

       

       <Columns>

           <asp:TemplateField HeaderText="Username">
                   <ItemTemplate>
                       <asp:Label ID="lbl2" runat="server" Text='<%#Bind("Username") %>'></asp:Label>
                   </ItemTemplate>
                   <EditItemTemplate>
                      <asp:TextBox ID="txtName" runat="server" Width="140px" Text='<%#Bind("Username")%>'></asp:TextBox>
                  </EditItemTemplate>
                   <ItemStyle HorizontalAlign="Center" />
               </asp:TemplateField>
            <asp:TemplateField HeaderText="UserType">
                   <ItemTemplate>
                       <asp:Label ID="lbl3" runat="server" Text='<%#Bind("UserType") %>'></asp:Label>
                   </ItemTemplate>
                   <EditItemTemplate>
                      <asp:TextBox ID="txtName" runat="server" Width="140px" Text='<%#Bind("UserType")%>'></asp:TextBox>
                  </EditItemTemplate>
                   <ItemStyle HorizontalAlign="Center" />
               </asp:TemplateField>

              <asp:TemplateField HeaderText="Delete User">
                   <ItemTemplate>
                        <span onclick="return confirm('Are you sure to Delete the record?')">
                       <asp:Button ID="btnDelete" runat="server" CommandName="Delete" Text="Delete" />
                   </ItemTemplate>


                   <ItemStyle HorizontalAlign="Center" />
               </asp:TemplateField>
                   <asp:TemplateField >
                   <EditItemTemplate>
                        <asp:Button ID="btnCancel" runat="server" CommandName="Cancel" Text="Cancel" />
                   </EditItemTemplate>
                   <ItemStyle HorizontalAlign="Center" />
               </asp:TemplateField>


           </Columns>
       </asp:GridView

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
       {
           //int Id = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Values[0]);
           Label Username = GridView1.Rows[e.RowIndex].FindControl("lbl2") as Label;
           Label Usertype = GridView1.Rows[e.RowIndex].FindControl("lbl3") as Label;
           string constr = WebConfigurationManager.ConnectionStrings["ConnectString"].ConnectionString;
           using (SqlConnection con = new SqlConnection(constr))
           {
               using (SqlCommand cmd = new SqlCommand("[Sp_InsertUserRegisteration]"))
               {
                   using (SqlDataAdapter sda = new SqlDataAdapter())
                   {
                       cmd.CommandType = CommandType.StoredProcedure;
                       cmd.Parameters.AddWithValue("@Action", "DELETE");
                       cmd.Parameters.AddWithValue("@Username", Username);

                       cmd.Parameters.AddWithValue("@Usertype", Usertype);
                       cmd.Connection = con;
                       con.Open();
                       cmd.ExecuteNonQuery();
                       con.Close();
                   }
               }
           }
           this.BindData();
       }