Help! Domain mapping not working after moving a client...

I use domain mapping on the multi-site. It's been working great but today we had to make some changes on the server and now I can't get it to work.

History: These domains were in CPanel as "add on" domains - but they had their own zone files so I simply pointed the A record and all worked well.

Now, they have new zone files - I went in and pointed the A record but the sites don't come up any more.

Any ideas?