Why can't I sign into the Support Communities on iOS unless I'm using Chrome?

I'm in Safari, on this website, and I see Welcome, Guest | Sign In in the upper left corner. I tap Sign In, and get brought to the screen where I enter my ID and Password. I enter both, and get right back to the Home page, but I am not signed in! Nothing tells me I entered any information wrong. What's wrong with Safari? I am currently typing this on Chrome on my iPod touch. When I use Safari, I can't sign in. Any suggestions?