[ATTACK OF THE B TEAM MODS]

I made an attack of the b team server for my friends.  They can join, but the problem is that none of the mod items are working.  Place down an item belonging to a mod, it disappears.  Adding a mod item to the inv will come up with it does not exist, something like that.  Please help me.

[Downloaded a map to go on this modpack]

I've downloaded a map on this modpack, the map was successful but the mods didn't work. The mods showed up in the inventory screen but can't use the mod items. Please help me on this.