Need Help Debuging - Space Shooter Tutorial

I have been following along with the Unity tutorial for the space shooter game
(http://unity3d.com/learn/tutorials/projects/space-shooter/counting-points)
and made it halfway through this tutorial and somehow my hazards (asteroids) are no longer appearing on my screen. I am new to scripting and wondering if anyone can guide me in the right direction as far as finding out how to figure out what may be causing this. This scripts I changed during this tutorial are 100% fine but, I'm thinking I must have tweaked something in the inspector on the Unity end.

Any ideas?
Thanks in advance.

 

Ok so now it magically works again, not sure why. For learning purposes, I would still love to get feedback on how to deal with this in case I encounter such a problem again. (Because I am 100% sure something similar will happen in the future lol).