Space Button wont map to anything.

[Rayxzz]

So I'm trying to play my copy of Super Mario Galaxy on my PC. 

It works flawlessly but as soon as I tried to configure my space button to Z, it would not allow me to do so.
Do you know how to fix this?



Version used: Dolphin Emulator 5.0 - 10061
Laptop used: Alienware 17 r5 

[Billiard26]

Press space ONCE then wait out the timer for 3 seconds.

[Rayxzz]

Press space ONCE then wait out the timer for 3 seconds.

Thanks, had no idea that I had to wait it out for 3 seconds. It works now