Level Unlock System....frustrated,Building a level unlock system using player prefs

Hi everyone,

Currently having a very frustrating time trying to get my level unlock system to work.

The scoring premise of my game is very simple. It is a gem match game and if you receive a certain score you are awarded 1, 2 or 3 stars. A very similar nature to the angry birds scoring system. I want my game to progress to the next level if you achieve 2 stars or above.

I have my level manager working fine and my level select scene working fine however I am having so much difficulty trying to integrate the lock and unlock feature. I have tried to do this many times using the player prefs system.

I have been trying to integrate this feature for days and having little to no success with it. Any help or advice is hugely appreciated.