When there is no growth on the substrate, we suggest reading this article on mushroom grow kits that do not grow. 

After 21 days we recommend using the "Cold Shock" technique to kickstart the development of the mushrooms.

Here is how you do a Cold Shock :

1. Take the full grow kit (inside the closed grow bag) and put it in the refrigerator (2 - 7°C) for one night (8-12 hours). 
2. After this time, place the grow kit back on the original warm spot. 
3. Wait a few days till a week before the pins start to show.