Java Card

Hi,

i have a strange problem with "usim" command class on windows 7.
i make a software for reading data from sim cards (SIM and USIM) and before reading data, i check if the file 2F00 (EFdir) exist with GSM11.11 commands (A0 A4 00 00 02 2F 00).
if the file exist, i assume that is an USIM and switch to GSM31.102 (CF ETSI TS 102 221 doc).

example of command/answer in XP:

-> A0 A4 00 00 02 2F 00 #select 2F00 in gsm11.11 command
<- 9F 0F # OK
#the file exist so i switch to gsm31.102 command
-> 00 A4 00 04 02 3F 00 #select MF in gsm31.102 command
<- 61 29 # send get response with 29 as P3.

same commands in W7:

-> A0 A4 00 00 02 2F 00 #select 2F00 in gsm11.11 command
<- 9F 0F # OK
#the file exist so i switch to gsm31.102 command
-> 00 A4 00 04 02 3F 00 #select MF in gsm31.102 command
<- 6E 00 # class not supported

i don't know why it doesn't work in seven.
if the card doesn't support command class change during session why it work in XP ?

i was thinking about reseting the card before changing command class, but it seem that i need to wait about 10sec before reconnecting to the card or i still get 6E 00 error.

any idea about the problem source ?