[Nut-upsuser] can't make mustek powermust 600usb work

[Alex Girchenko]

Disclaimer: I've setup APC UPS monitoring and it works...
... but when it comes to mustek powermust 600usb (connected via
com-port), I can't make it work.
Got NUT installed via aptitude in ubuntu feisty and a basic setup,
exactly the same as for the apc, except for the name of the ups and
the corresponding section of ups.conf
--
[mustek]
        driver = megatec
        port = /dev/ttyS1
        desc = "Mustek PowerMust 600USB"
--
# upsc mustek at localhost
Error: Driver not connected

Tried changing the port value to ttyS1, but this won't work either.
Any suggestions?

Thanks.