Gamemode isn't deriving fretta

[Silverah!]

When I try to play my fretta gamemode(deathmatch) on my GMod server, it doesn't derive fretta.
And I did typ: sv_gamemode deathmatch in console.
But I do have fretta in my C:\srcds\orangebox\garrysmod\gamemodes folder.
Here's my shared.lua(deathmatch), I hope you guys could help :).

[I]DeriveGamemode( "fretta" )

IncludePlayerClasses()

GM.Name = "Deathmatch!"
GM.Author = "[UF] Silverah!"
GM.Email = ""
GM.Website = ""
GM.Help = "Simple Deathmatch!"

GM.GameLength = 30
GM.MaximumDeathLength = 1
GM.MinimumDeathLength = 1
GM.RealisticFallDamage = true
GM.EnableFreezeCam = true
GM.SelectColor = true
GM.ShowTeamName = false
GM.NoPlayerTeamDamage = false
GM.FragLimit = 20

function GM:CreateTeams()

team.SetUp( 1, "Deathmatchers", Color( 70, 230, 70 ), true )
team.SetSpawnPoint( 1, "info_player_start" )
team.SetClass( 1, { "Deathmatcher" } )

end[/I]

,Silverah

PS: In singleplayer it works fine.