With changing my name

So, I decided to change my MC username. So I go onto the site    namemc.com.

And I see there is a lot of 3 letter names not taken. So I go onto minecraft.net. And I go to change my name, and then is says that the name is not available! When is says its available on namemc.com. idk if its a bug or what! But I need this username. Should it work like this?