Level UP your toys....
I can't level up a toys on my computer at all. WHY?
I too at first was not able to level up Toys. But then when i equipped Toy to to girl, i was able to level up Toy from Toy window - It was either this step that helped OR it was some game update which made it work, i am not sure of it.
So bro you can try to level up equipped Toy first and see that it would work or not.