declarative #Bind doesn't bind in update command

I have a bunch of controls like the following in the EditItemTemplate of a ListView, with LINQDataSource:
<asp:TextBox ID="Email" CausesValidation="true" EnableViewState="False" Font-Bold="false" Text='<%#Bind("Email")%>' BackColor="#FFFFFF" Enabled="true" TabIndex="50" runat="server" /> I'm curious to know why the database won't update on the click of the Update button:
<asp:Button ID="btnUpdate" CommandName="Update" Text="Update" UseSubmitBehavior="False" TabIndex="170" runat="server" /> According to all I've read, the above code should be sufficient. Since CommandName is set to Update, it would seem that no code-behind is necessary.
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