Elements display inconsistant

Sorry about this-- figured it out, I wasn't adding a !-- comment -- tag in the content field.

I just added 13 header elements to a website. 10 of them worked, three don't. I did the same for all 13. I've checked and double-checked and I've done the same thing every time. The pages affected are very similar. To check, I created a simple text page but couldn't get a header to display on it either.

Here's my site: http://www.thehmc.ca

The pages "About..." and "Join..." have headers which won't display. The others all work except one called "Youth Camps" (bottom menu), which also doens't work.

Any help appreciated.