OOP Issues

[TheMetamorphics]

So I'm trying to simulate using classes in Garry's Mod Lua. I've created the class, but cannot instantiate an object in another file even though I've included the class's file in the other file. Can anybody tell what's going wrong with the class?
tss_SpriteTrail = {}
tss_SpriteTrail.__index = tss_SpriteTrail

function tss_SpriteTrail:new(ent, attachmentId, numberOfTrails, color, additive, startWidth, endWidth, lifetime, textureRes, texture)

  local newSpriteTrail = {
    ent = ent,
    attachmentId = attachmentId,
    numberOfTrails = numberOfTrails,
    color = color,
    additive = additive,
    startWidth = startWidth,
    endWidth = endWidth,
    lifetime = lifetime,
    textureRes = textureRes,
    texture = texture,
    infoEntities = {}
  }

  for i = 0, numberOfTrails, 1 do

    local infoTarget = ents.Create("info_target")
    infoTarget:Spawn()
    infoTarget:Activate()
    infoTarget:SetParent(ent, attachmentId)
    infoTarget:SetLocalPos(Vector(math.random(0, 0), math.random(-10, 10), math.random(-55, 5)))

    util.SpriteTrail(infoTarget, 0, color, 0, startWidth, 0, lifeTime, 1/startWidth*0.5, texture)

  end

  setmetatable(newSpriteTrail, tss_spriteTrail)
  return newSpriteTrail

end

function tss_SpriteTrail:remove()
  timer.Create("tss_spriteTrailRemove_"..self:EntIndex(), 5, 1, function()
    SafeRemoveEntity(v)
  end)
end

setmetatable( tss_SpriteTrail, { __call = tss_SpriteTrail.new })