Luci, glad I was able to help, sorry I didn't have time to put up the links. It sounds like the sealing gasket got 'pinched' and has a little wrinkle that didn't seat properly - pull the top back off and make sure that the gsket is in correctly - this skould take care of it. If you need more help, just ask

BTW did you try further tightening (with a wrench on both the nut and the bolt?) with the system off?