[AccessD] MULTI SELECT LISTBOX dynamically selecting values from another listbox

I think my brain has turned to toffee this morning.....
I need to have multiple values select selected in a listbox from another 
listbox
By selecting a line from the first listbox which contains the id's I then 
need those lines to appear selected in a second listbox
For example my first listbox has a field with data in the form 
73221,7259,13771,2
My second listbox contains those (and other)values
5698
7259
13771
2
73221
996589
23
38
and so on

I choose the line in the first listbox I want the four lines selected in the 
second box

The code below works fine for the single value but I need to loop thru the 
values in my first line to make it work.....should be simple but I simply 
cant get it to work

Dim intI As Integer
        Dim strIDValue As String
        strIDValue = 73221
        For intI = 0 To Me!listcon1.ListCount - 1
           If Me!listcon1.ItemData(intI) = strIDValue Then
              Me!listcon1.Selected(intI) = True
           End If
        Next intI
This code will select line 73221

Any suggestions?

TIA

Tom Keatley