Get the sum of data table column in repeater Footer

Question

Hello

i'm trying to get the sum of column [Exit Units] in a repeater

with dataTable as datasource, i used to do like that in Page_Load:

if (!IsPostBack)
    {
        DataTable dt = (DataTable)Session["CheckedRows"];
        Repeater1.DataSource = dt;
        Repeater1.DataBind();
        foreach (RepeaterItem item in Repeater1.Items)
        {
            if (item.ItemType == ListItemType.Item ||item.ItemType == ListItemType.Footer)
            {
                Label lblExitSum = (Label)item.FindControl("lblExitCount");
                string sum = dt.Compute("sum(ExitUni)", string.Empty).ToString();
                lblExitSum.Text = sum;
            }
        }
    }

 but the output is strange and doesn't appeare in the footer after the last row like this:

 

 

Item No	Goods Description	UOM	Exit Units	Units New Balance	WT Balance	Exit WT	Exit Amount(LC)
S440862340A	C RAMP AW165 PAINT-S440862340A	????	1	1.000000	0.365000	0.182500	146.797040
2
F1SEMIAUTO0441	C.TO F1-L-16-M 220/240 50HZ MF C.CONT-F1SEMIAUTO0441	????	1	1.000000	1.160000	0.580000	1772.856560

 

 

the total of the column is 2 but it appears after the first row