NT driver Porting Problem... Pl. Help!!!!!

Hi all,
I am currently porting my driver running on win '95 for an ISA
card to NT platform.
HALTRANSLATEBUSADDRESS function returns "unmapped", with the same
bus address as the mapped address.
Although the driver is executing READ_PORT_USHORT() and WRITE_PORT_USHORT() calls with valid address and data, the CARd does not seem to get any signals as subsequent read of same location in memory of card yeilds random values and writes are not effective.
Any light on what could be possibly happenning, seeking for your advice.

Thanking you,
bsmanoj