I tried to sort the Recordset but it doesn't display correctly.
Anything when wrong with my codes as follows:

Set rsCustLookup = New ADODB.Recordset
With rsCustLookup
.CursorLocation = adUseClient
.Open "SELECT * FROM Customer",cnn1,adOpenKeyset,adLockOptimistic
.Sort = CustID
.Requery
End With

Set dcCustIDList.RowSource = rsCustLookup
dcCustIDList.ListField = "CustID"
dcCustIDList.Refresh