Skipping / Not Extruding?

Hi, I just recently leveled my build plate, and my printer is now skipping when printing. I have seen other have this same problem but haven't been able to find the cause. Here is an example of what I mean (note this isn't my print, it's another image I found of the same problem). Does anyone have any idea what could be causing this?

http://i.imgur.com/M7GVPru.jpg

This seems like more of an extruder issue than having to do with your build plate. Could it just be a coincidence that it started happening after leveling the plate? Have you tried releveling the plate?

I would look more at the extruder. Is it clean? Is the motor functioning correctly?