You need to dose it with a good ammonia source if you're going fishless. It won't automatically cycle without some ammonia for bacteria food. If you want to go automatic, pick up a good sized shrimp at your local supermarket and place it in a stocking in the tank and leave it to rot. The rotting will produce ammonia which in turn will drive the cycle.
You can find some good ammonia at Ace hardware (Ace Janitorial grade ammonia) if you've got an Ace close to you. Dose to 4-5 ppm
and then wait until it drops to 1 ppm
. Then continue dosing to approx 1-2 ppm
every 12 hrs until the cycle completes.