Friends can't see my spawned items on my server. HELP

[Samtc99]

So me and my friend made a Gmod local server to play together. We both downloaded this vehicle add-on pack and it works for both of us in single player. But when he joins my server i can spawn them but to him they show as errors. And when i go to his server he can spawn them but they just show up as errors to me. So it only works for one of us o each of our servers. Can somebody please show a solution. Thanks!

[[2S]Cookies!!]

Are you sure it's the same vehicle

[Samtc99]

[QUOTE='[2S]Cookies!!;43762743']Are you sure it's the same vehicle[/QUOTE]
Positive, we downloaded the same pack. Its just weird that the person that isn't hosting isn't able to use them and even see them. When he hosts it i get errors even though i have the add-ons. And when i host he can't get them.