NdisMRegisterIoPortRange() failure

There are some ports (0x2e, 0xf00) which we need to access with
our NDIS miniport, and we do the good thing of calling
NdisMRegisterIoPortRange(). However, this fails (returns
NDIS_STATUS_FAILURE), but, since we *have* to use these ports,
we ignore the failure and we keep plugging along (driver
works fine). Note that we’ve tried this specifying either
an Isa or Internal for the BusType (for NdisMSetAttributes()),
with the same results.

Question is:

a) how to debug this? how can I find who’s got them or
why the miniport can’t get them?

b) since we ignore failure, what potholes lurk ahead?
(besides the one where someone else is already using these
ports, which I don’t believe so)

Note that this works the same on either NT4 or W2K.

Any help appreciated.

Pete