Creating event and erros "c is null"

Scheduler Javascript
#1

This is the video showing the erros
http://www.youtube.com/watch?v=pe5LK3IkAok

Here is the viewer

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The problem is the erros just show in some rows and some not.Please help me :blush:
Thanks for reading this :slight_smile:

#2

I solve it myself by replace mycell2 instead of mycells