DEX Pad problem

Hi there.
I have converted my NAND PS3 to DEX 4.20. Everything works like a charm except one issue. When I set in Debug Settings BD emulation (USB) on, I can't use my game controller on console start. i.e. I press PS button to start the console, console starts, pad lights are blinking but won't connect to my console.
In other modes console starts well and controller connects to it.
What's wrong?
Thank you.