Move Data Files to a 2nd disk

[Salam ELIAS]

Hi, Currently I have my mySql data in var/lib/mysql. I added a 2nd disk, called data at mnt/salam/mySqlData/ to my box, copied
var/lib/mysql
to
mnt/salam/mySqlData/mysql
Changed the owner to mysql and my user to read and write.
Changed the datadir in my.cnf to reflect the new directory.
When I start mysqld it erros and refuses to start.
What else I should do? Thanks