Elevator: Source slot machines

[AlphaBarney]

I've seen one or two thread about them but they weren't helpful at all. Basically I'm trying to make the slot machines work but they seem to be conflicting with ULX (they work then ulx admin mod is removed).
Here is the error:

[ERROR] gamemodes/cinema/entities/entities/slotmachine/init.lua:238: attempt to index local 'ply' (a nil value)
  1. SendPlaying - gamemodes/cinema/entities/entities/slotmachine/init.lua:238
   2. unknown - gamemodes/cinema/entities/entities/slotmachine/init.lua:179

Here are the lines at which the errors are occuring :

/*---------------------------------------------------------
	Slot Machine Functions
---------------------------------------------------------*/
function ENT:GetPlayer()

	local ply = player.GetByID( self.SlotsPlaying )

	if IsValid(ply) && ply:IsPlayer() && self:IsInUse() then
		return ply
	end


end

function ENT:SendPlaying()
	
	if ( !IsValid( self ) || !IsValid(self.chair) ) then return end

	self.SlotsPlaying = self.chair:GetDriver():EntIndex()
	self.LastSpin = CurTime()
	
	local ply = self:GetPlayer()
	ply.SlotMachine = self -- 238 is here -------------
	
	local rf = RecipientFilter()
	rf:AddPlayer( ply )
	
	umsg.Start("slotsPlaying", rf)
		umsg.Short( self:EntIndex() )
	umsg.End()
	
end

and

function ENT:Use( ply )

	if !IsValid(ply) || !ply:IsPlayer() then
		return
	end
	
	
	if !self:IsInUse() then
		self:SetupVehicle()
	
		if !IsValid(self.chair) then return end -- just making sure...
	
		ply.SeatEnt = self.chair
		ply.EntryPoint = ply:GetPos()
		ply.EntryAngles = ply:EyeAngles()
		
		ply:EnterVehicle( self.chair )
		self:SendPlaying( ply )  -  179 is here --------------
	else
		return
	end
	
end

Anyone knows if ulx sometimes conflicts with anything in these codes?

Thank you.