Setting multiple items as selected in a ListBox with c#

[waldedg]

I have a ListBox set as Multiselect. I am populating the table thruough asp.net code. But I am using another dataset to get the items that should be selected. The only item that ends up selected is the last item in the dataset. The code I am using for setting the selected items is:

DataSet ds1 = SqlHelper.ExecuteDataset(ConnStr, "StoredProd", Parm);

lbRequestTime.SelectionMode = ListSelectionMode.Multiple;

foreach (DataRow row in ds1.Tables[0].Rows)
{
lbRequestTime.SelectedValue = row["PerfTimeId"].ToString();
}

Any help on how to get the Mulitple selected items selected would be great.
Doug