Why is my 'Admin Commands' Chat function not executing the command?

Yes, I am developing another Admin Commands system, but only with a better, and cleaner type of code [Different from my other ones, where they have allot of code], however, something is not executing the command, for example, when I attempt to say in the Studio, :kill player, it will not execute the command for some reason, but, when I type in reset, it will fire that command. Sadly, I am very confused on why it is doing this, and why it is not executing the command, I am thinking the error is at line 46, but I am not too sure, as that is supposed to prevent someone who is not an Admin from using the :kill player command. Here is the code I am currently using;

local Admins = {
['TheeDeathCaster'] = true;
['Player'] = true;
['yournamehere'] = true;
[44391621] = true;
}

local Banland = {
['someoneyouhate'] = true;
[40265333] = true;
}

local Prefixes = {":",";","/","_"}

function ChkPrefix(str)
local Prefix = "";
for i = 1, #Prefixes do
for x = 1, #str do
if str:sub(i,i) == Prefixes[i] then
Prefix = str:sub(i,i)
break
end
end
end
if Prefix ~= "" then
return Prefix
else
return false
end
end

function GetPlr(str)
local plrz = {};
for i,v in pairs(game.Players:GetPlayers()) do
if str ~= "" and (v.Name:lower():find(str) == (1)) then
table.insert(plrz,v)
end
end
return plrz
end

function Chats(plr,msg)

if (msg:lower():find("reset") == (1)) then return false, plr:LoadCharacter() end

if not Admins[plr.Name] and not Admins[plr.userId] and not ChkPrefix(msg) then return false end --Line 46, where I think the error is, although, this is where it is supposed to prevent a 'Non-Admin' to use the ':kill player' command
local Len = ChkPrefix(msg); msg = msg:sub(Len:len()+1) --Gets the length of the 'msg' of where the 'Prefix' is, then allows you to execute the command below;

if msg:lower():find("kill ") then
local chk1 = msg:lower():find("kill ");
local plrz = GetPlr(chk1+1);
for i,v in pairs(plrz) do
if v.Character then
v.Character:BreakJoints()
end
end
end

end

function AdminControl(plr)
if Admins[plr.Name] or Admins[plr.userId] then print(plr.Name," is an Admin!") end
if Banland[plr.Name] or Banland[plr.userId] then plr:Destroy() print(plr.Name," is currently banned.") end
plr.Chatted:connect(function(msg) Chats(plr,msg) end)
end

game.Players.PlayerAdded:connect(AdminControl)
for i,v in pairs(game.Players:GetPlayers()) do AdminControl(v) end

If you need me to tab my code correctly/better, I'll do it as soon as possible.