hi there , this is my first discussion so please don't kill me if I do something wrong
I have a in metasploit when i do :

msf > db_driver mysql [*] Using database driver mysql
msf > db_connect metasplotit
[-] Error while running command db_connect: Failed to connect to the database: uninitialized constant MysqlCompat::MysqlRes

Call stack:
/opt/metasploit3/msf3/lib/msf/ui/console/command_dispatcher/db.rb:1598:in `db_connect_mysql'
/opt/metasploit3/msf3/lib/msf/ui/console/command_dispatcher/db.rb:1445:in `cmd_db_connect'
/opt/metasploit3/msf3/lib/rex/ui/text/dispatcher_shell.rb:246:in `run_command'
/opt/metasploit3/msf3/lib/rex/ui/text/dispatcher_shell.rb:208:in `block in run_single'
/opt/metasploit3/msf3/lib/rex/ui/text/dispatcher_shell.rb:202:in `each'
/opt/metasploit3/msf3/lib/rex/ui/text/dispatcher_shell.rb:202:in `run_single'
/opt/metasploit3/msf3/lib/rex/ui/text/shell.rb:143:in `run'
/opt/metasploit3/msf3/msfconsole:117:in `<main>'

I think that it's a mysql problem but I don't find any solution on google... can u help me please? thanks a lot