@ 3sixthy
as far as i know SonyEricsson phone uses Memory stick (Pro, Duo, and the latest is M2: Memory Stick Micro)
isn't it?
CMIIW
@ miskin
i also have the similar problems with standard TF from E398 package (64mb).
i try to read it w/ my PC and it can read the TF. and then i try format it many times (FAT).
but when i turn it back to my e398 it can't detect.
in my opinion u should try are_goenk's suggestion by using another phone to format it.
if it not work either, sorry maybe ur TF is broken.
CMIIW