Public GUIText isn't allowing me to put a text in

So I've been taking the Roll A Ball tutorial for Unity, and I have come almost to the end and have encountered a problem.

I have a public GUIText set, but when I try to drag ANY of my text in, the doesn't allow me to. I don't know what is wrong, it happened to me the last time I tried to take the class. Last time I gave up trying because everything was the same in the script but it didn't work.

I have tried making it a prefab(the text), tried creating new text, but nothing is working! I have double checked my code multiple times...all of it is right and is working except for that. There are no errors either.

 

Bump! Please, I would like to finish this tutorial and move on!