gridview ne passe pas en edition

bonjour

je bute depuis ce matin sur un probleme bien curieux.

ma page aspx :

<asp:DataGrid ID="dgTEZ" runat="server" AutoGenerateColumns="False"
OnItemDataBound="dgTEZ_ItemDataBound" Width="952px" CellPadding="4"
ForeColor="#333333" GridLines="None" OnEditCommand="dgTEZ_EditCommand">

<Columns>

<asp:EditCommandColumn EditText="Edit" CancelText="Cancel"
UpdateText="Update" />

<asp:TemplateColumn>

<ItemTemplate>

<asp:CheckBox ID="CBTEZ" runat="server" />

</ItemTemplate>

<EditItemTemplate>

<asp:CheckBox ID="CBTEZ" runat="server" />

</EditItemTemplate>

</asp:TemplateColumn>

<asp:BoundColumn DataField="nom" HeaderText="Nom" ReadOnly="true" />

<asp:BoundColumn DataField="statut" HeaderText="Statut" ReadOnly="true"/>

<asp:BoundColumn DataField="IP" HeaderText="IP" ReadOnly="true"/>

<asp:TemplateColumn HeaderText="Type" >

<ItemTemplate><%#Eval("typeTEZ") %>

<asp:Label ID="lbypeTEZ" runat="server" Width="120px"></asp:Label>

</ItemTemplate>

<EditItemTemplate><asp:DropDownList runat="server" ID="ddlType">

<asp:ListItem Text="TEZ_IP" Value="TEZ_IP" Selected="True"></asp:ListItem>

<asp:ListItem Text="TEZ_Radio" Value="TEZ_Radio"></asp:ListItem>

</asp:DropDownList></EditItemTemplate>

</asp:TemplateColumn>


</Columns>

<FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />

<EditItemStyle BackColor="#999999" />

<SelectedItemStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333"
/>

<PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center"
/>

<AlternatingItemStyle BackColor="White" ForeColor="#284775" />

<ItemStyle BackColor="#F7F6F3" ForeColor="#333333" />

<HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />

</asp:DataGrid>



touts'affiche normalement mais si je clique sur le bouton edit la page se
rafraichit mais le gridview disparait .

ou me suis je trompé???



merci pour toute aide.