Forms Data Controls :: Display Image In Gridview?

I want to display in image in gridview .

this is gridview

<asp:GridView ID="gvDetails" runat="server" AllowPaging="True" >
<Columns>
<asp:TemplateField HeaderText="Cover">
<ItemTemplate>
<asp:Image Height="200px" Width="150px" ID="imgSaved" runat="server" ImageUrl='<%#DataBinder.Eval(Container.DataItem, "cover") %>'
AlternateText='<%#DataBinder.Eval(Container.DataItem,"BookName") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="BookID" HeaderText="Book ID" SortExpression="BookID" />
here is the problem
<asp:Image Height="200px" Width="150px" ID="imgSaved" runat="server" ImageUrl='<%#DataBinder.Eval(Container.DataItem, "cover") %>'
AlternateText='<%#DataBinder.Eval(Container.DataItem,"BookName") %>' />
</Columns>
</asp:GridView>

i want to display cover in gridview. datattype of cover is varbinary(Max).my image is stored in database as varbinary. but image is not display.all other fields are displaying fine.this is the code

DataSet ds = new DataSet();
SqlDataAdapter adp;
adp = new SqlDataAdapter("SELECT * FROM BooksDetails", conn);
ds.Clear();
adp.Fill(ds, "BooksDetails");
gvDetails.DataSource = ds;
gvDetails.DataBind();