Bug: SMP Jetpack Building

When i build a Jetpack in SMP, something weird happens. I am able to put the components into the crafting table, and able to grab the Jetpack(empty) with my mouse. But as soon as I pick it up, it snaps back into the crafting table, and all the components come back, as if nothing happened. I've already built and flown a Jetpack in single player, and all other features work fine in SMP. Help!