IIRC the cheap USB<->PP converters support only printers, they don’t behave like a real PP and usually don’t work with other devices (like scanners, HW keys needed to run some software and so on).
Either try another USB converter (read the specs carefully or try it before buying!) or buy a PCI card (all of them should have “real” PP).
(I noticed that when I was looking for an USB<->PP converter for my old HP LJ5L, some product descriptions mentioned that…)