Why isn't my iPod touch's calendar showing up in iCloud?
I had a similar problem with an iPad Calendar that wouldn't sync with [e.g., appear on] my other devices.

I found this link helpful:

http://forums.macrumors.com/showpost.php?p=13675190&amp;postcount=9

In my case, I turned off iCloud Calendar syncing on the iPad [in iCloud settings].  I then chose to keep the Calendar data on the iPad rather than delete it.

Next, I turned iCloud Calendar syncing back on in iCloud settings, chose Merge, and bingo, everything appeared everywhere.  

Hope this helps.