You didn't tell us what reader you use.
If it is internal reader the syntax is for the lower card reader:
SMARTCARD SID ASSIGN : /dev/sci0 0 { 0df3,0df4,0df5 }
upper card reader:
SMARTCARD SID ASSIGN : /dev/sci1 0 { 0df3,0df4,0df5 }
smargo on a linux pc:
SMARTCARD SID ASSIGN : /dev/ttyUSB0...