giving a entity a trail

[Sev456]

ive tried using other trail codes from madcows weapons pack and others but mabye its not compatible with it or something every time its says null entity can you please just add a line to the code to make a trail with the colors 217 213 235 255 laser.vmt
trail start size .95 end size .5

heres the code

AddCSLuaFile( "cl_init.lua" )
AddCSLuaFile( "shared.lua" )
include( "shared.lua" )

function ENT:Initialize()

self.Entity:SetModel( "models/weapons/bt_762.mdl" )

self.Entity:PhysicsInit( SOLID_VPHYSICS )
self.Entity:SetSolid( SOLID_NONE )
self.Entity:SetMoveType( MOVETYPE_VPHYSICS )

local phys = self.Entity:GetPhysicsObject( )

if phys:IsValid( ) then
phys:EnableGravity( false )
phys:Wake( )
end

self.Start = CurTime( )

end

function ENT:PhysicsUpdate( PhysObj )

if self.Start < CurTime( ) - ( 10 / GetConVarNumber( "phys_timescale" ) ) then
self.Entity:Remove( )
return
end

local Trace = {
start = self.Entity:GetPos( ),
endpos = self.Entity:GetPos( ) + ( self.Entity:GetForward( ) * 20 ),
filter = self.Entity
}

local TraceRes = util.TraceLine( Trace )

if TraceRes.Hit or TraceRes.HitWorld then

if TraceRes.Entity:GetClass( ) ~= "physical_bullet" then

local Bullet = {
Src = self.Entity:GetPos( ),
Dir = self.Entity:GetForward( ),
Spread = 0,
Num = 1,
Damage = self.Damage,
Force = self.Force,
Tracer = 0,
TracerName = "Pistol"
}

self.Owner:FireBulletsOld( Bullet )

self.Entity:Remove( )

return false

end

end

PhysObj:SetVelocity( self.Entity:GetForward( ) * 10000 )

end