Please perform the following:
1. From the ActiveClient GUI (with the card inserted): Double click on the "My Certificates" icon. Are your certificates present? If so, select Tools->Advanced->"Make My Certificates Available to Windows".
2. Try again.
3. If it does not work, do this (in order): reinstall the card reader driver, and then reinstall the Active Client software. Having the very latest driver from the manufacturer is very important.
4. Try again.
5. If that does not work, try moving the card reader to another port (if USB), or try using another reader all together.
Also, make sure that there is no other card reader driver installed on the system. This has been known to mess with Active Client.