Hello All,

I did not realize that the plus key does not work like other keys.  I suspect you might have to check for whether or not the shift key is also held down.  I am currently putting together the lecture for this week so I do not have time to investigate the matter right at this moment.  If anyone finds a solutions please feel free to post it here.

In the meantime, those of you who are already working on the lab, it is ok to change the plus key to K_EQUALS (the equal key).  This will work for sure. 

The only problem with using the plus key on the numpad is that my Surface for example does not have a numpad so this may not work for all keyboards equally.