Gnupg and cardreader

[gabriel @ telenet]

I have installed Gnupg 1.4.9 and Enigmail 1.3.5 on a Mozilla Thunderbird
10.0 mail client. My OS is Windows 7.
Everyting works just great (can send and receive encrypted mails).
When I try to use my cardreader (ACR38U), which by the way works fine
with websites that require ID cards, I get an error:

"Your SmartCard reader could not be accessed
Please attach your SmartCard reader, insert your card, and repeat the
operation"

Is there a way to make that work?