cannot view contacts list creating a new mail

I have upgraded outlook from 2003 to 2007. When I create an email and
click on the "To..." button to select an address I get an empty list.
I have tried to import the pst file and I have also tried to add the
pst file in the data manager and I still cannot select from the
contacts list. If I select "Contacts" I can see all of the contacts
and contact folders I just cannot see them when I am creating a new
email. Any help would be most appreciated.

thanks

john