Try printing out the objIndex and see if you're getting the number correctly. Also, make sure object names are correctly set. If names are not matched, picking doesn't work.

The keys can be picked up without setting it solid so probably something is wrong in your checkObject method! Solid areas just determine if it stops character movements. You should still be able to get the index of the item even if it's not solid.

It sounds like the attack input is recognized but not correctly set off. Follow the movement of your key input and see what's being wrong. If you still can't figure it out, I'd recommend rolling back your code until the point the issue doesn't happen then try implementing it again.