[DotNetDevelopment] Invalid postback or callback argument

[Ana]

Hello everyone,

I have a GridView as follows:

--
<asp:GridView ID="GridView1" AutoGenerateColumns="False"
DataKeyNames="ID"
        OnSelectedIndexChanged="GridView1_OnSelectedIndexChanged"
runat="Server"
        Width="800px" PageSize="35" AllowPaging="true">
        <Columns>
            <asp:TemplateField HeaderText="Title">
                <ItemTemplate>
                    <asp:Label ID="TitleLabel" runat="server" Text='<
%#Eval("Title")%>' />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Move" ItemStyle-
HorizontalAlign="Center">
                <ItemTemplate>
                    <asp:Button ID="MoveUpButton" Text='<%#
Server.HtmlDecode("Up &uarr;") %>' runat="server"
OnClick="MoveUpButton_Click" /> &nbsp;
                    <asp:Button ID="MoveDownButton" Text='<%#
Server.HtmlDecode("Down &darr;") %>' runat="server"
OnClick="MoveDownButton_Click" />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:ButtonField Text="Details..." HeaderText="Show
Details" CommandName="Select" ItemStyle-HorizontalAlign="Center">
            </asp:ButtonField>
        </Columns>
    </asp:GridView>
--

What is happening is, when I click on MoveUp Button I have this error
message:

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.  If the data is valid and expected, use the
ClientScriptManager.RegisterForEventValidation method in order to
register the postback or callback data for validation.

The error occurs before the MoveUpButton_Click method be called. This
method is in the code behind but do nothing at this moment.

--
Protected Sub MoveUpButton_Click(ByVal sender As Object, ByVal e As
System.EventArgs)

End Sub
--

What is happening here? What is wrong? Why I'm having this error?

Thanks,

Ana