Addons involving custom trades are impossible to trade to!

I play in my Huawei Y6 Pro and I use addons like Modern Tools or Mine-Machines add on. For some reason, I can't trade with them. A button displays to trade but when I click it, nothing happens. It also happens when I make my own custom trade add on with shoulders when I was making my own addon. I don't know if anyone else is facing this. Thanks in advance!