Help Creating a Rain Collector

I am trying to create a simple rain collector, the way i am going in to make 2 blocks, 1 where that player can interact (Empty) and one where the player can right click with a bucket to collect water, the second part is done and working, what i m trying to do now is to make the empty block convert to a full version when its raining 

This is what i make, and for i dont understand what is going wrong here, but it doest work (This is place on block tick update)