Another way to handle it, Just add following code before binding Gridview.
And also you should use to add show footer="true" in Gridview.
DataSet ds = new DataSet();
da.Fill(ds);
gvrecords.Columns[7].FooterText = (from row in dt.AsEnumerable()
select row.Field<double>("ActualWt")).Skip(gvrecords.PageIndex * gvrecords.PageSize).Take(gvrecords.PageSize).Sum().ToString("C", culmoney).Remove(0, 2).Trim();
gvrecords.DataSource = ds;
gvrecords.DataBind();
</double>
In your Html Page Make these Changes, Just Add Show footer as True
<asp:GridView runat="server" ID="gvrecords" AutoGenerateColumns="false" ShowFooter="true" HeaderStyle-BackColor="#7779AF" HeaderStyle-ForeColor="White" DataKeyNames="DocketNo" Width="80px">