Try the regulator seat seal/oring. This will cause issues, especially if it is old and you took the valve apart. The compression grooves need to line up or it will leak. Those grooves are created over time by being compressed between the valve halves and molded in place around the raised edge of the valve. Once you take the valve apart, if you disturb the alignment, it will never seal properly after. Therefore, you need to replace it regularly if you take your valve apart alot.
Except for the Automag in front, its usually the man behind the equipment that counts.