Problems flashing S55 with v.20

[extin]

I've tried to flash my S55 with v.20 fubu. The problem is that after flashing the phone doesn't start up, only powers on and beeps then powers off.
When I flash my original FW16 everything works. So how do I flash the v.20 correctly.

Here's how I've done so far:
Power off
Connect cable
Load v.20 .fls to v_klay buffer
Start writing
Anwer yes to the question if the bootcore should be written.
Write success
Turn on, above happens

Doing the same on original fubu, made with v_klay, it works.

So what am I doing wrong? And how should I do it before I experiment on my own and kill my phone

[Chris02]

Just use v20 WINSWup Update!

U will get it from www.gsm-multifund.de