Mysql – Increase InnoDB buffer pool size

I am having difficulty setting the buffer pool size and log file size for MySql InnoDB. I am far from a MySql expert but have been reading around and it seems that to change this I just add these lines to my /etc/mysql/my.cnf

# Set buffer pool size to 50-80% of your computer's memory
innodb_buffer_pool_size=2048M
innodb_additional_mem_pool_size=512M
#
# Set the log file size to about 25% of the buffer pool size
innodb_log_file_size=256M
innodb_log_buffer_size=128M

The server has about 7GB of memory and is also running a web server so I think these numbers should be an okay starting point. After saving and restarting the server however it does not seem that the changes have taken effect. I tried running Mysqltuner which reported that the buffer pool is still at 16.0M. Any idea what I am doing wrong? Let me know if you would like to see more of the config file.
Thanks!