Piwik doesn't recognize my MySQL server host

During the third step of the piwik installation, Piwik shows me this error :

Error while trying to connect to the database server:
SQLSTATE[HY000] [2005] Unknown MySQL server host ‘X.X.X.X’ (3)

I use the lastest version downloaded from the git. I didn’t have this error when I used the version from piwik.org. I moved to that version because I want to develop a specific plugin.

Please, can someone help me with this ? I spent too much time on that issue …

Can you connect to ‘X.X.X.X’ (exactly as stated in the original error message) from command line on the piwik host?

I finally moved to another server more suitable for dev. The one I used had a firewall which I didn’t configure. Thank you anyway for the answer !