System.InvalidCastException: Object cannot be cast from DBNull to other types.

I am getting this sudden error at below Label inside Gridview:

<ItemTemplate>
     <asp:Label ID="lblAmount" class="acAmount" runat="server" Text='<%# string.Format("{0:#,##.00}", Convert.ToDouble(Eval("Amount")))  %>'></asp:Label>
</ItemTemplate>

Please let me know how to solve it. Please reply