at the unofficial PSR 8000 site I wrote a warning about 72pin EDO RAM. I also installed 64 MB EDO RAM and my PSR 9000 recognized only 16 MB (the same amount as yours). Fortunately I had in my computer a pair of old 32 MB 72 pin (non EDO) RAM, which was recognized without problems. To be quite sure, then I tried once again another pair of 32 MB EDO RAM and they also were not recognized (not at least 16 MB).
Therefore I assume, that the PSR 9000 has problems with the recognition of the EDO RAM and I would recommend you to use old non EDO RAM.
Hope this helps
P.S.: Micco, SDRAM are 168pin, they cannot be used in the PSR 9000.