Gridview inside another gridview

<asp:GridView runat="server" ID="GrdAmMaster" AutoGenerateColumns="False" CssClass="fontstyleGrd"
                        BackColor="White" BorderColor="LightGray" BorderStyle="Solid" BorderWidth="1px"
                        CellPadding="1" Width="900px" AllowPaging="True" DataKeyNames="SrNo" ShowHeader="false">
                        <HeaderStyle BackColor="Black" ForeColor="#fcbf04" />
                        <Columns>
                            <asp:TemplateField HeaderText="View">
                                <ItemStyle Width="30px" />
                                <ItemTemplate>
                                    <asp:LinkButton ID="lbRmView" Text="View" CommandArgument='<% # Eval("SrNo")%>' CommandName="View"
                                        runat="server" CssClass="grdlink">
                                    </asp:LinkButton>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <%--<asp:TemplateField HeaderText="Sr.No.">
                                <ItemStyle Width="50px" HorizontalAlign="Center" />
                                <ItemTemplate>
                                    <%#Container.DataItemIndex+1%>
                                </ItemTemplate>
                            </asp:TemplateField>--%>
                            <asp:BoundField HeaderText="Sr.No." DataField="SrNo" ItemStyle-Width="40px" ItemStyle-HorizontalAlign="Center"></asp:BoundField>
                            <asp:BoundField HeaderText="Activity Name" DataField="AmName" ItemStyle-Width="300px">
                                <ItemStyle Width="300px"></ItemStyle>
                            </asp:BoundField>
                            <asp:BoundField HeaderText="UOM" DataField="AmUOM" ItemStyle-Width="200px"></asp:BoundField>
                            <asp:TemplateField HeaderText="ManPower" ItemStyle-Width="200px">
                                <ItemTemplate>
                                    <asp:Panel ID="pnlAmChild" runat="server">
                                        <asp:GridView ID="GrdAmMasterChild" runat="server" Width="400px" ShowHeader="false" BorderWidth="0px">
                                            <Columns>
                                                <asp:TemplateField HeaderText="Sr.No.">
                                                    <ItemStyle Width="30px" HorizontalAlign="Center" />
                                                    <ItemTemplate>
                                                        <%#Container.DataItemIndex+1%>
                                                    </ItemTemplate>
                                                </asp:TemplateField>
                                                <asp:BoundField HeaderText="Designation" DataField="AmDesig" ItemStyle-Width="170px"></asp:BoundField>
                                                <asp:BoundField HeaderText="Numbers" DataField="AmNumbers" ItemStyle-Width="100px"></asp:BoundField>
                                            </Columns>
                                        </asp:GridView>
                                    </asp:Panel>
                                </ItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                        <PagerStyle HorizontalAlign="Center" />
                        <RowStyle Width="100px" />
                    </asp:GridView>

Protected Sub BindAmMasterGrid()
        Try
            ObjCls.LoadGrid(GrdAmMaster, "SELECT Distinct SrNo, AmName, AmUOM FROM BOQActivityMasterMst WHERE EmpSrNo = '" & Session("ESrNo") & "'", "BOQActivityMasterMst")
        Catch ex As Exception

        End Try
    End Sub
    Protected Sub GrdAmMaster_RowDataBound(sender As Object, e As GridViewRowEventArgs) Handles GrdAmMaster.RowDataBound
        Try
            If e.Row.RowType = DataControlRowType.DataRow Then
                Dim SrNoC As String = GrdAmMaster.DataKeys(e.Row.RowIndex).Value.ToString()
                Dim gvOrders As GridView = TryCast(e.Row.FindControl("GrdAmMasterChild"), GridView)
                ObjCls.LoadGrid(gvOrders, "SELECT Distinct SrNo, (select DesName from DesigMst where SrNo = AmDesig) as AmDesig, AmNumbers from BOQActivityMasterDet where RefSrNo = " & SrNoC & " and EmpSrNo = '" & Session("ESrNo") & "' Order By SrNo", "BOQActivityMasterDet")
            End If
        Catch ex As Exception

        End Try
    End Sub