Populate List Box from Combo in DAP

Hej,

I have a combo box and a list box , i have created in Data Access Pages , i want to populate the values of the listbox by selecting a value from the combo box , then after the values are populated in the list box , i want to choose a value from it and then goto another DAP where i can edit that record.

It does not populate the values for the listbox at all...
I have the code , it works fine in Forms but when i do this is DAP it does not work at all it gives me errors that makes no sense... below is the code ( i did not write this code bymyself but took it from somewhere) , its been 3 days now but i just cant get it to work anyway , anyone just show me the way (i have no experience in Visual Basic):


On the Combo box's onafterupdate property:
If IsNull(Me.cboPlants) Then
Me.cboUnits = Null
Me.cboUnits.Enabled = False
Me.cboUnitsLocked = True
Else
Me.cboUnits.Enabled = True
Me.cboUnits.Locked = False
Me.cboUnits.Requery
End If

On a Button to generate the results :
Dim rownum As String
Dim myfilter As String
If Me.[cboUnits].ItemsSelected.Count = 0 Then
Exit Sub
Else If
For Each rownum In Me.[cboUnits].ItemsSelected
myfilter = myfilter & "[Plant ID] = '" & Me.[cboUnits].Column(0, rownum) & "' OR "
Next rownum
If Right(myfilter, 3) = "OR" Then
myfilter = Left(myfilter, Len(myfilter) - 4)
Else
End If
DoCmd......(i could not open another record in DAP at all)

best regards,
solig