about samsung nandflash maker id!

I have a samsung nandflash, connect like that:

D0~D7： D0~D7
ALE： A3

        CLE：            A2
        #CE：            #CE6    （adds: 0x400000）
        #WE：            #WR
        #RE：            #RD
        Ready：          K54

and I use mtd nand drivers from uClinux-dist-20030522. Firstly, I want test the nandflash Maker id and Device id in nand_scan():
...
...
nand_select(); //just set *(volatile unsigned char *)0x400004 = 0xff;

*(volatile unsigned char *)0x400004 = 0x90;
*(volatile unsigned char *)0x400008 = 0x0;

nand_maf_id = *(volatile unsigned char *)0x400000; nand_dev_id = *(volatile unsigned char *)0x400000;
...
...

But, when I print the nand_maf_id and nand_dev_id, they are always 0x41 and 0x42. according the Manufacture document, the maker id is 0xEC and
the device id is 0x53. I want know what else I must be done.
thanks!