Also - can I have problems IF keyboard adapter's chip hole didn`t FIT well on real Amiga chip for keyboard? When I opened my case, I found that there were several wires wired over the chip, so I could connect Amiga4000 keyboard [on my towered A1200]... So I removed wires and I suppose because of wires weight - it didn`t fit well. Can this be the case of non working Tab key?
Well I have a lyra2 4000 myself (it connects to the a4000 keyboard port), but I had the same problem with the \ key. I dind't test the TAB key before installing the Win_usa keymap.
When I used the Win_Usa keymap all my keys were recognised.
However the lyra2 has some default settings, but you can change this.
See
http://www.icomp.de/l2.
For Example : The Amiga keyboard has the two braces [ and ] in the top left corner of the numeric keypad, therefore Lyra 2 always maps the NumLock key the the opening brace [. Right next to the NumLock key, the regular PC keyboard has the slash or divide key. By pressing F5 in configuration mode, you toggle between two choices: Either the divide key transfers a closing brace ] to the Amiga, or it transfers the keycode for the forward slash (divide key) to the Amiga.
You can configure this when pressing LShift + pause.
Also by installing the mmkeyboard software, you can make use of the multimedia keys of your keyboard.
Edit: You must test the TAB key in a texteditor, input prefs won't do anything when you press it.