Is the problem that it's not being run?
things inside the lua/server folder aren't autorun.
You need to place your file in garrysmod/lua/autorun/server
The table thing that BlueNova posted is a much better way of doing it instead of an if statement though, but if you want the player to spawn with it each time, you still need to use the PlayerLoadout hook, InitialSpawn would only give it to them when they joined the server but not if they died and respawned.