[NaClchemistryK]

Some people here don't know what the code of the gamemode is. So we can't tell. As the user ball said, you can use rcon command for that. The rcon commands are built into samp servers. If you don't know how to use rcon, then this is how:
Go on your server.
type /rcon login [rcon password] <-- to log into rcon. Always works.
then use /rcon hostname [name] <-- to change the hostname.
And also, you don't need a rcon command in your script, as I said it is built into samp servers.