LOL it is probably just me missing something.

For a test I setup NotEnoughItems-1.7.10-1.0.3.74-universal and adventurebackpack-1.7.10-0.8c. I gave got a cow pack. I then closed the game and removed NotEnoughItems-1.7.10-1.0.3.74-universa. Started up the game again and was not able to put on the pack.

Earlier I had also noted that the adventure suit recipe was not shown in NotEnoughItems.

Thanks.

I have the same problem,
I am using Curse and for testing I created a custom profile with forge 10.13.2.1230 and MC version 1.7.10 with only this mod. I cannot equip it in the chest-plate slot.
As the FAQ suggested I also reinstalled the mod. still nothing :(

The mod looks amazing btw.

Ok, my apologie for the spam but I found the solution.

• place the backpack on the ground
• While holding shift (crouching) break the backpack
• It will be on your back (test with F5) NOT in your chest plate slot.
  Wich is awesome because that leaves room for protection ^^

This isn't a bug, if you right click with the pack in hand and click the equip button on the backback gui it will equip. This button becomes an unequip button while on the back and the sleeping bag button while on the ground.