self is nil

[MrBerlin]

Hiho, here my code for the class:

BattleRecord = {};
BattleRecord.__index = BattleRecord;
 
setmetatable(BattleRecord, {
  __call = function (cls, ...)
    return cls.new(...)
  end,
});
 
function BattleRecord.new(tamerId, petSpeciesIds, attackIds, triesTable)
  local self = setmetatable({}, BattleRecord);
  self.tamerId = tamerId;
  self.petSpeciesIds= {{1,2,3},{4,5,6}};
  --self.petSpeciesIds = petSpeciesIds;
  self.rounds={};
  self.attackIds = {};
  self.tries = {0,0};
  if (triesTable ~= nil) then
    --self.tries = triesTable;
  end
  print("battleRecord init SElf:"..(tostring(self) or "nil"));
  return self;
end
function BattleRecord:GetTriesTable()
    return self.tries;
end
function BattleRecord:GetSuccessRate()
    
    print("self: "..tostring(self));
    if (#self.tries == 0) then
        return 0;
    end
    if (self.tries[2]>0) then
        return Math.ceil(self.tries[1]/self.tries[2]);
    end
    return 0;
end
function BattleRecord:PrintRound(round)
    local str = "Round: "..round..": ";
    local trainer = self.trainers[1];
    local roundTable = self.rounds[round];
    if (#roundTable>0) then
        local pet = trainer:GetPet(self.orders[round][1]);
        local orderType = self.orders[round][2];
        local orderValue = self.orders[round][3];
        local orderTypes = {"", " uses ", "got switched to ", " used a trap ", " skipped the turn "};
        str = str..pet:GetName();
        str = str..orderTypes[orderType];
        if (orderType==2) then 
            local abilityId, abilityName = C_PetBattles.GetAbilityInfoByID(pet:GetAbilityId(orderValue));
            str = str..abilityName;
        else
            str = str..orderValue;
        end
    else
        str = str.."no Action";
    end
 
    print(str);
end
function BattleRecord:PrintAll()
    print ("--- BATTLE RECORD ---");
    print ("[TamerID: "..self.tamerId.."][NumRounds: "..#self.rounds.."][Successrate: "..self.GetSuccessRate().."%]");
    print ("Teams:");
    for t = 1, 2 do 
        local teamTable ={};
        local str = " Team "..t..": [";
        for p = 1, #self.petSpeciesIds[t] do
            local id = self.petSpeciesIds[t][p];
            local info = {C_PetJournal.GetPetInfoBySpeciesID(id)};
            teamTable[p] = info[1];
        end
        str = str..table.concat(teamTable, ", ");
        print(str);
    end
    for i=1, self.GetNumRounds() do
        self.PrintRound(i);
    end
end
function BattleRecord:GetRound(roundIndex)
    return self.rounds[roundIndex];
end
function BattleRecord:GetTamerId()
    return self.tamerId;
end
function BattleRecord:GetSpeciesId(ownerIndex, petIndex)
    return self.petSpeciesIds[ownerIndex][petIndex];
end
function BattleRecord:AddRoundTable(roundTable)
    self.rounds[#self.rounds+1] = roundTable;
end
function BattleRecord:GetNumRounds()
    return #self.rounds;
end
function BattleRecord:AddRound(activePet, orderType, orderValue)
    if (orderType~= nil) then
        self:AddRoundTable({activePet, orderType, orderValue});
    else
        self:AddRoundTable({});
    end
end

when i run it and the BattleRecord:PrintAll() is called it gives me this error:

Date: 2014-12-25 21:13:24
ID: 1
Error occured in: Global
Count: 1
Message: ..\AddOns\CounterPet\class_BattleRecord.lua line 30:
   attempt to index local 'self' (a nil value)
Debug:
   CounterPet\class_BattleRecord.lua:30: GetSuccessRate()
   CounterPet\class_BattleRecord.lua:63: PrintAll()
   CounterPet\class_Battle.lua:63: End()
   CounterPet\CounterPet.lua:31:
      CounterPet\CounterPet.lua:24
Locals:
self = nil
(*temporary) = <function> defined @Interface\FrameXML\RestrictedInfrastructure.lua:116
(*temporary) = "self: nil"
(*temporary) = <function> defined =[C]:-1
(*temporary) = true
(*temporary) = "attempt to index local 'self' (a nil value)"

Why is self nil in the BattleRecord:GetSuccessRate? *veryconfused*