You can also try downloading Wugfresh's Nexus root toolkit, as there is a function to correct this problem. Both ways work quite well, as I have run into your issue personally. Good luck.
Droid OG (Retired), Droid 2 (Retired), Droid 3(Retired), Droid X (Retired), Droid X2 (Retired)
Samsung Galaxy Nexus (Unlocked, Rooted, Overclocked, Undervoltaged), Samsung Galaxy Tab 10.1 (Stock)
Nexus 7 (Unlocked, Rooted, Undervoltaged)
Please click "Thumbs up" if somebody posts something helpf