Attaching external display to MacBook Pro through VGA → DVI → Thunderbolt I am trying to attach an external monitor to my MacBook Pro using VGA to DVI adapter and then DVI to Thunderbolt. 

I have MacBook Pro 2012 with Retina display and the monitor is Acer V223HQV.

Problem is that when I connect it the external monitor doesn't start working but is visible under System Preferences → Displays. Anyone can help me out here? What extra information I can give you to help solve this problem?
It's not possible because the Mini-Displayport ("Thunderbolt") to DVI adapter outputs a DVI-D (digital-only) signal, while DVI to VGA adapters work by taking the analog signal out of DVI-I (digital+analog).

You'll need a Mini-Displayport to VGA adapter.