memory detection error

I used Mandrake 7.2 with kernel 2.2.17mdk.
The problem is that the kernel can’t detect
all my memory. It shows it as 32M when it should be 64M. I’ve tried editing lilo.conf
and change the line “append=32M” to “append=64M”. After I run /sbin/lilo and restarted the computer, everything goes haywire and Mandrake couldn’t recognize the mouse anymore. Does anybody have any idea what is goin on here and how to solve the memory problem?