Check for a wall between two players?

Not sure if I can use util.QuickTrace for this.

[lua]
local ply1_pos = ply1:GetPos()
local ply2_pos = ply2:GetPos()
local tr = util.QuickTrace(ply1_pos, ply2_pos:Sub(ply1_pos), {ply1})
if tr.HitWorld then
//there is a fucking wall
end
[/lua]

Oh, HitWorld.

Thanks.