I have 2 RN4081 and have had this same problem some times...here's what I did...

Change to a new full charged batt.
If this does not work. Boil some watter and put the atomizer in it for about 3 mins or so...let it air dry for about 20 min. Then blow it out with canned air...this has brought back a few atomizers from the dead for me and they work GREAT!!

Hope this helps a little...
-Trey