How do I get the rest of a string after a sequence?

What I need is help getting the end of a string, in my script when a player uses a pattern in the chat it shows the player's name and the message after the pattern, the problem is that it only shows the name and not the pattern after the sequence. Here is the script I am using:

local admins={"ultrabug", "FredeyFly"}
game.Players.PlayerAdded:connect(function(np)
	for i,v in pairs(admins) do
		if np.Name==v then
			np.Chatted:connect(function(msg)
				if string.sub(msg, 1, 2)=="m/"then
					cmt=np.Name..": "string.sub(msg, 3)
					cm(cmt)
				elseif string.sub(msg, 1, 5)=="kill/"then
					plr=game.Players:findFirstChild(string.lower(string.sub(msg, 6)))
					if plr ~=nil then
						Kill(plr)
					end	
				end
			end)
		end
	end
end)
function cm(text)
	local label=Instance.new("TextLabel")
	local sg=Instance.new("ScreenGui")
	for a,b in pairs(game.Players:GetChildren())do
		plabel=label:Clone()
		psg=sg:Clone()
		psg.Parent=b.PlayerGui
		plabel.Parent=psg
		plabel.Size=UDim2.new(1, 0, 1, 0)
		plabel.Text=text
		plabel.BackgroundColor3=Color3.new(0, 0, 0)
		plabel.BorderColor3=Color3.new(255, 0, 0)
		plabel.TextColor3=Color3.new(255, 0, 0)
		plabel.TextScaled=true
		plabel.BackgroundTransparency=0.5
		wait(6)
		psg:Destroy()
	end
	label:Destroy()
	sg:Destroy()
end
function Kill(player)
	player.Character.Humanoid.Health=0
end