changing players names

hi i am killing myself with this one thing that i can't seem to get right. changing players names (i.e a player types a chat message like -set name *name here*) but i can't figure out how substrings work, and i can't find an unprotected warcraft 3 map that has this feature. plz help!! i have been trying for the past hour!! ty

GUI Trigger:

Player - Player 1 (Red) types a chat message containing -set name as A substring
Player - Player 2 (Blue) types a chat message containing -set name as A substring
Player - Player 3 (Teal) types a chat message containing -set name as A substring
Set s = (Substring((Entered chat string), 11, (Length of (Entered chat string))))
Player - Set name of (Triggering player) to s
Game - Display to (All players) the text: (Name of (Triggering player))

JASS Script:

function Trig_Melee_Initialization_Copy_Actions takes nothing returns nothing
    local string s = SubString(GetEventPlayerChatString(),11-1,StringLength(GetEventPlayerChatString()))
    call SetPlayerName( GetTriggerPlayer(), s )
    call DisplayTextToForce( GetPlayersAll(), GetPlayerName(GetTriggerPlayer()) )
endfunction

//===========================================================================
function InitTrig_Melee_Initialization_Copy takes nothing returns nothing
    set gg_trg_Melee_Initialization_Copy = CreateTrigger( )
    call TriggerRegisterPlayerChatEvent( gg_trg_Melee_Initialization_Copy, Player(0), "-set name ", false )
    call TriggerRegisterPlayerChatEvent( gg_trg_Melee_Initialization_Copy, Player(1), "-set name ", false )
    call TriggerRegisterPlayerChatEvent( gg_trg_Melee_Initialization_Copy, Player(2), "-set name ", false )
    call TriggerAddAction( gg_trg_Melee_Initialization_Copy, function Trig_Melee_Initialization_Copy_Actions )
endfunction

ahh tyvm! it works!! (i still don't understand how it works) but tyvm!!

I made a unprotected map of with this trigger going to upload it soon on this site, It's called Askaria... you can steal anything from my maps if you want. Unless it is protected like Sturlungar Final v.