Where did you get the 'cured' LR
from? IF it's from the LFS
you're probably ok. IF you got it mailorder there is going to be some die off during shipping and adding it to the tank will start a new cycle.
Are you taking water chemistry readings?
Ph, Ammonia, Nitrates and Nitrates at a minimum?
Get a couple of small powerheads and place them so they are aimed at each other or at the front of the tank so you get good water flow. You don't want circular flow, and you do want surface agitation.
You might also want to get some more LR
for filtration. Recommended 1-1/2 - 2 pounds per gallon of tank volume.
Also, have you done any partial water changes? Are you planning on doing regular partial water changes (10%/week aprox)?