debugging google-chrome javascript json

Google Chrome won’t let me place breakpoints

I’ve been using Google Chrome to debug my javascript, but then all of a sudden I can no longer place breakpoints. I click on the line number, where I previously clicked to add a breakpoint, but no breakpoint will be added. Sometimes if I click very fast, like a madman, I can see it trying to add breakpoints, but it won’t stick.

The only thing I changed was adding JSONView. I uninstalled that, but still can’t add breakpoints.

Does anyone have any idea?

An edit:
I can place breakpoints on other pages, like StackOverflow, just not the one I’m developing running on localhost.