Google Calendar not showing in page body

I’ve thrown an html brick into the body of my webpage and placed the code for a google calendar into the brick. The calendar shows up fine in Blocs, but not Safari or Chrome (and yes, the calendar’s set to “public” etc.)

Strangely enough, I can, however, get the calendar to show up on my browser if I add the html brick & iframe to the page’s header.

is this a bug, or am I messing something up?