can not set ListField poperty of a DataCombo control

Hi,

I am trying to set the ListField property of a DataCombo Control to a subset of values like in the code below.
DataCombo2 should display in the ListField the "id" values that satisfy a certain condition (Where clause in the SQL statement) from the "id" column in the "Nadfmm" table.
...but it boesn't happen! the ListField is empty, WHY?
PLEASE HELP ME.
here is the code I have written so far:
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Dim SQLString As String
Dim my_recordset As New ADODB.Recordset
Dim my_connection As New ADODB.Connection

Private Sub DataCombo1_Change()

SQLString = "SELECT Nadfmm.id FROM Nadfmm WHERE Nadfmm.board = """ & Me.DataCombo1 & """"

Set my_connection = New ADODB.Connection
my_connection.ConnectionString = "Provider =Microsoft.Jet.OLEDB.3.51;Data Source=C:\Documents and Settings\icgR225\My Documents\nadfmm97.mdb;"
my_connection.Open

With my_recordset

.Source = SQLString
.CursorType = adOpenDynamic
.CursorLocation = adUseServer
.LockType = adLockOptimistic
.ActiveConnection = my_connection
.Open , , , , adCmdText
End With

Set Me.DataCombo2.RowSource = my_recordset
Me.DataCombo2.ListField = "id"

my_recordset.Close
my_connection.Close

End Sub