Hello
This guide is the best place to start, as it covers most of the common issues for Mac.
Common OS X Smart Card troubleshooting steps
Specifically, you may want to try and go to terminal and type:
open /Library/Security/tokend
Next, in the directorty that opens, create a new folder. (lets say "Temp") and put the tokenD files in this new folder, all except the PIV.tokend.
Next, try again. If this does not work, please use the url above as it includes more detailed instructions on clean up, driver updates, etc.
I hope this helps!
Have a great day!
Ryan V.