I cant delete rows from Listview

Hi,  I am trying to handle basic insert ,Update ,delete operations using listview .I have a table with three field in the db.So I can insert and update .But I cant  delete any data .What is wrong wtih my code

<div> <asp:ListView ID="ListView1" runat="server" DataSourceID="SqlDataSource1" InsertItemPosition="LastItem"> <AlternatingItemTemplate> <tr style=""> <td> <asp:Button ID="DeleteButton" runat="server" CommandName="Delete" Text="Delete" /> <asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" /> </td> <td> <asp:Label ID="ImajIdLabel" ...