Column dont show any data in grid view

i have in grid view column that get product of tow cell the problem data in total amount column don't show any data
the rest data its displayed normally
<asp:DropDownList ID="dllorderid" runat="server" CssClass="form-control" DataSourceID="SqlDS_OerderID" DataTextField="Order_ID" DataValueField="Order_ID" AutoPostBack="True" AppendDataBoundItems="true" OnSelectedIndexChanged="dllorderid_SelectedIndexChanged"> <asp:ListItem Text="Select Order ID" Value="" /> </asp:DropDownList> <asp:GridView ID="GridView1" runat="server" CssClass="table table-bordered text-nowrap" AutoGenerateColumns="False" DataSourceID="SqlDs_Grid" DataKeyNames="Pro_ID" > ...