i would test your mysql database access from command line from remote machine
mysql -h vm-007.server.com -u testuser my_db -p
it will ask you for a password and type that in.
If it fails then you are probably dealing with a mysql setup problem.
likely you are dealing with something like the mysql daemon only listening to the localhost interface i.e. 127.0.0.1 . Even if it allows access from any host if it isn't listening to a give interface like eth0 it doesn't matter.