I’m new in digital signing concept, I’m developing a winform application that allow an user to select a certificate from windows certificate store, and use the selected certificate to sign to a pdf file, it is working perfectly when plug an usbtoken which contains the certificate and a midleware of the usbtoken installed, when i sign to a pdf file the midleware promt me for entering pin and after enter the correct pin my application can easyly sign to the pdf file. But when I try with a smartcard( TokenMe Evo – Bit4id) I can still get the certificate from windows store but when create signature by bellow line of code: