I can't use certain items

Hi
I can't use some objects, even if I think I meet the requirements.
Like here
This is signature stone for 3 star mutant character. And I have 3 star mutant character.

Why I can't use it?

Or this one, this is an item which changes your 2 star character in to 3 star. Character must be fully upgraded.

And again I have one. This is my spider man fully upgraded and I can't use this item.

What's wrong?
I can't use some objects, even if I think I meet the requirements.
Like here
This is signature stone for 3 star mutant character. And I have 3 star mutant character.

Why I can't use it?

Or this one, this is an item which changes your 2 star character in to 3 star. Character must be fully upgraded.

And again I have one. This is my spider man fully upgraded and I can't use this item.

What's wrong?
2
Comments
the second one is a rank up gem from rank 2-3. your spiderman is already rank 3, so you cannot use it. the champion must be rank 2 and max level
Use it on a rank 2 max level 2 stars.
Understood or should I explain in detail
the next one is rank. 4-6 stars have 5 ranks, 3 stars have 4, 2 stars have 3, and 1 stars have 2 I think. you can increase those ranks by using catalysts, but the champ must be max level for that rank. the
final one is levels, which have even more numbers. those can be increased with iso-8.
so say I pull a new 3 star. they are rank 1, level 1. I then use iso to level them to 3 star, rank 1, level 10. I use catalysts to take them to 3 star, rank 2, level 1. I then use catalysts to take them to 3 star, rank 2, level 20. I rank them and level them up all the way to 3 star, rank 4, level 40. this is the highest you can level up a 3 star champ, and you cannot bring them to 4 star
I hope that helps. tag me if you need further clarification
But also for Dup'd champs (silver stars, not gold), if they are already at Maximum Sig Level (ie, 99) then it will not let you use additional Sig Stones on those champs either.