ASP.NET Must declare the scalar variable เกิดจากการ delete ใน grideview ต้องการลบ row ที่เลือก ผิดตรงไหนคะ

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
                            Height="107px" Width="333px" AllowPaging="True" 
                            CellPadding="4" ForeColor="#333333" GridLines="None" PageSize="20" 
                            ShowFooter="True" 
                            style="margin-right: 0px" DataSourceID="SqlDataSource">
                            <PagerSettings Mode="NumericFirstLast" PageButtonCount="5" Position="Top" />
                            <RowStyle BackColor="#EFF3FB" />
                            <Columns>
                                <asp:BoundField DataField="typecalno" HeaderText="typecalno" 
                                    SortExpression="typecalno" />
                                <asp:BoundField DataField="technicalname" 
                                    HeaderText="technicalname" SortExpression="technicalname">
                                </asp:BoundField>
                                <asp:CommandField ShowEditButton="True" ShowDeleteButton="True" />
                                <asp:CommandField ShowDeleteButton="True" />
                            </Columns>
                            <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                            <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Right" />
                            <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
                            <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                            <EditRowStyle BackColor="#2461BF" />
                            <AlternatingRowStyle BackColor="White" />
                        </asp:GridView>
			            <asp:SqlDataSource ID="SqlDataSource" runat="server" 
                            ConnectionString="<%$ ConnectionStrings:ServiceManagement %>" 
                             
                            SelectCommand="SELECT typecalno, technicalname FROM TECHNICIAN ORDER BY typecalno DESC" 
                            DeleteCommand="DELETE FROM TECHNICIAN WHERE typecalno = @typecalno"
                            
                            UpdateCommand="UPDATE TECHNICIAN SET typecalno = @typecalno, technicalname = @technicalname WHERE (typecalno = @typecalno)">
                            <DeleteParameters>
                                <asp:Parameter Name="typecalno" />
                            </DeleteParameters>
                            <UpdateParameters>
                                <asp:Parameter Name="typecalno" />
                                <asp:Parameter Name="technicalname" />
                            </UpdateParameters>
                        </asp:SqlDataSource>