Login Button fails on Mobile when using Facebook App

When I'm using the iOS Facebook app, and I click on a link to my website, the Facebook Login Button doesn't work; it just stalls.

I'm in the Facebook app >> I click on my fan page and click on the website's link on the About section >> I'm taken to my webpage ... however, Facebook keeps me in its walled garden >> I click on your Facebook Login button >> it opens a blank page and then just stalls...

Since FB will be a primary source of traffic for my site, I'm sort of concerned about this.

Thanks for your help!