mmmm...I might know what is going on. I have watch some more tutorials and in kicked me that there are no common grounds in my previous design. By adding them, now it seems to work. I can cause a current from 0 to 3.75A.
I literally spend a couple of hours not knowing what was going on until now. Sorry for bringing this post up. Anyway its a great thread so why not 
![2015-08-02 21_22_28-Livewire - Professional Edition - [dummy load_simple.lvw _].jpg](https://europe1.discourse-cdn.com/arduino/original/3X/1/9/19d1f9230105f7641c9d465e40a5a936c7684cd7.jpg)