14.04 - mysql-server:Depends: mysql-server-5.5 but it is not going to be installed

I am using ubuntu 14.04 on VirtualBox. I try install mysql-server using command sudo apt-get install mysql-server, i always got error like below:

Some packages could be installed .This may mean that you have 
request an impossible  situation or if you are using the unstable
distribution that some required packages have not yet been created 
or been moved out of Incoming.
The following packages have unmet dependencies:
mysqsl-server : Depends: mysql-server-5.5 but it is not going to be installed
E:Unable to correct problems, you have held broken packages.

and then i try use some command like below :

sudo apt-get update
sudo apt-get upgrade
sudo apt-get clean
sudo apt-get autoclean
sudo apt-get purge mysql-server*
sudo apt-get install mysql-server

but it still error. Please help me!