I saw someone else had this problem and I did not see it satisfactorily
answered:  

I have Outlook 2002, SP3

Desire:  To create a DL from existing Contact Address Book by selecting
members.  When I click "Select" button, only some names are added.  There are
blanks with a ";" for others.  When I open the properties for each, I do not
see any difference in the information entered in the fields.

Additionally, as with the previous writer, when I create a new message and
click on the "To" box which brings up my contact address book, and then
highlight these same names and click "To", only some show up in the "Message
recipients" box; the same ones that will show up in my new distribution list.
For the others, only the ";" appears.  It's like they are ghosts!  Any idea
what is happening?