render.DrawSprite creates an ugly black square

[mitterdoo]

I am trying to draw a sprite, but when I use glow02, the one I want, it shows up incorrectly and draws a black square box. It won't even show up green, when I set the fourth argument for render.DrawSprite to Color(0,255,0,255). Here's my code:
[lua]
include("shared.lua")
local glow=Material("sprites/glow02")
function ENT:Draw()
self:DrawModel()
local light=math.Round(self:GetLight())
if light==1 then
render.SetMaterial(glow)
render.DrawSprite(self:GetPos()+Vector(3,0,-12),10,10,Color(0,255,0,255))
end
end
[/lua]
Any help?

[editline]8/8/13 1:56 PM[/editline]

Fixed. I had to assign glow to a material created with CreateMaterial().