Grid View Checkbox Checked Off Database Value

I get an error of

Specified cast is not valid

when I try to run my syntax. What I am wanting to do is if the value in the database is yes check the checkbox, if it is no, then do not check the checkbox. Here is my HTML that shows how I am trying to do such:

<asp:GridView runat="server" ID="dg123" AutoGenerateColumns="false" CssClass="DataGrids" GridLines="Both" ShowFooter="true">
<FooterStyle CssClass="DataGridFooters" /><HeaderStyle CssClass="DataGridHeaders" />
<Columns>
<asp:BoundField DataField="abc" HeaderText="Alpha" />
<asp:BoundField DataField="efg" HeaderText="Echo" />
<asp:TemplateField>
    <ItemTemplate><asp:CheckBox ID="Completed" runat="server" Checked='<%#Eval ("Completed") %>'/></ItemTemplate>
</asp:TemplateField>
</Columns>

Where in the example above, abc efg and Completed are all fields in the database.