Filling textbox

private void fillParty()
        {
string selectPartyCmd = string.Format("SELECT DISTINCT [Cust_Name] FROM [CUSTOMER] where [Loc_Id] = '" + Program.locId + "'");
                txtPName.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
                txtPName.AutoCompleteSource = AutoCompleteSource.CustomSource;
                AutoCompleteStringCollection coll = new AutoCompleteStringCollection();
                coll = qc.txtAutoCollection(selectPartyCmd);
                txtPName.AutoCompleteCustomSource = coll;
}