ucos+Nichestack TCP/IP stack problem in DE2

The Vendor ID has not read successfully as it's supposed in the DM9000A data sheet which has indicated as below:

write 0x28 to the index port, then read from data port, we should have got 0x46

but I always get 0xC07 whether reading from the index port or data port after writting the value 0x28 to the index port. would it be the timing issue? I have added the dm9000 _INSTANCE and _INIT to the file "alt_sys_init.c" manually.