Distribution (category) lists in Livemail

I've created several group lists in live mail however when I send emails to the lists, it only sends the email to a few on the list.   I've recreated the lists with no success.   When I see the lists on the left hand side of the contacts display it shows the total on the list and when I open the list it is correct however when I click to edit the list then it only shows the few that would be sent.    How do I correct this?