Update...

Hi again. Been busy at work so I didn´t have time to test all proposals you gave me.
But now it´s finally done. I have tested three different firewire cables. I have also tested my enclosure on a firewire PCI card equiped with Texas Instr. chip, on a IBM box with Agere firewire chip and at last on a Dell box also equiped with TI chip. Non of these setups were able to recognise my NEC 3500 in enclosure.

Now I need your advice. This enclosure burns very good (i my opinion, excellent) when connected to USB2. Firewire connection (option) is clearly of no use to me.
I can RMA this enclosure, but I dont know what kind I will get in replacement...
So here are my alternatives.
1. I keep these enclosure and ask seller for reduction in price.
2. RMA´s this enclosure and hope (pray) for the "best" replacement, (other firewire chip).

Any advice much appreciated.

Finally one example how this enclosure burns YUDEN000T02 at 16x, fw 2.16 stock. Time: 6:24