@alfkil
Software and documentation is available at
http://phase5.a1k.org/Make sure that your SCSI bus is correctly terminated as described in the manual.
Run UnitControl and click on Rescan. You should either get a very detailed error report or the device appears.
If the device appears in UnitControl only after a rescan, then your settings in the Esc menu are not correct.
If you get an error report, then something regarding the hardware is not correct, probably termination. But read the error report and try to understand it.
A firmware update, even if you flash the same version as you already have, is a good way to reset all options in the Esc menu to default.
Do not "try more combinations". Read the documentation, find out the one correct combination and use that. Using wrong settings will not only not work but may even damage your devices.