about upgrade help me

i have rhor , i want upgrade it again, but when i synthesis rhor and want to upgrade , i can't , i have 2 rhor but i can't upgrade it , why ? anyone know ?
i upgrade my rhor 2 times , and want to upgrade again but i can't

If you already upgrade Rhor twice, then he is a silver medal Rhor. To upgrade a silver medal monster, you need to use a bronze monster.

So you need to get another Bronze Rhor (yes, that means you need to level him to 50 and enhence to S grade and feed another Rhor to him) before you can upgrade your Silver Rhor.

If you already upgrade Rhor twice, then he is a silver medal Rhor. To upgrade a silver medal monster, you need to use a bronze monster.

So you need to get another Bronze Rhor (yes, that means you need to level him to 50 and enhence to S grade and feed another Rhor to him) before you can upgrade your Silver Rhor.

thank you so much my friend