I have a we data tree, bound to a hierarchical data source, and on NodeBound event I am setting the Template ID for the node.  This is working well, and my template has a number of command buttons in it.

When I click on any of the buttons I get an error:

Invalid postback or callback argument.  Event validation is enabled  using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page.  For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them.

this is the code for my tree:

<ig:WebDataTree ID="wdtMyPlans" runat="server" InitialExpandDepth="0"  EnableConnectorLines="false"  StyleSetName="Office2007Silver"
                 onNodeBound="wdtMyPlans_NodeBound" EnableAjax="true" EnableHotTracking="true" BackColor="Gainsboro" OnItemCommand="wdtMyPlans_ItemCommand"  >
            <ClientEvents  NodeHovered="NodeHoveredHandler" NodeUnhovered="NodeUnhoveredHandler" />
            <Templates>
                <ig:ItemTemplate ID="tptNormal" runat="server" TemplateID="tptNormal" >
                    <Template>
                        <div style="width:270px; text-align:left; vertical-align:middle; color:Black; background-color:Gainsboro ">
                            <div style="float:left; vertical-align:middle; "  runat="server" id="divNode">
                                <asp:Label ID="txtPlanName" Width="180px" Font-Size="8pt"   runat="server" Text='<%# Eval("name") %>'></asp:Label>
                                <div id="divButtons" class="Gone" runat="server">
                                    
                                    <asp:ImageButton ID="btntEditPlan" runat="server"  ImageUrl="~/Images/pencil16.png" ImageAlign="Middle"
                                        ToolTip="Edit this plan" CommandName="EditPlan" CommandArgument='<%# Eval("WorkoutPracticePlanId") %>' />
                                   
                                    <asp:ImageButton ID="btntDeletePlan" runat="server" ImageUrl="~/Images/delete16.png" ImageAlign="Middle"
                                        ToolTip="Archive this plan" CommandName="DeletePlan" CommandArgument='<%# Eval("WorkoutPracticePlanId") %>' />
                                   
                                    <asp:ImageButton ID="btntViewPlan" runat="server"  ImageUrl="~/Images/view16.png" ImageAlign="Middle"
                                        ToolTip="View this plan for a specific athlete" CommandName="ViewPlan" CommandArgument='<%# Eval("WorkoutPracticePlanId") %>' />
                                   
                                    <asp:ImageButton ID="btntAssignPlan" runat="server"  ImageUrl="~/Images/group.png" ImageAlign="Middle"
                                        ToolTip="Assign this plan to athlete(s)" CommandName="AssignPlan" CommandArgument='<%# Eval("WorkoutPracticePlanId") %>' />                               
                                </div>
                                <div style="font-size:7pt; margin-left:20px"><%# Eval("description") %> </div>
                            </div>
                        </div>
                    </Template>
                </ig:ItemTemplate>
                <ig:ItemTemplate ID="tptFocus" runat="server" TemplateID="tptFocus">
                    <Template>
                        <asp:Label ID="txtSportName" Width="180px" Font-Size="8pt"   runat="server" Text='<%# Eval("name") %>'></asp:Label>
                    </Template>
                </ig:ItemTemplate>
            </Templates>
        </ig:WebDataTree>