Parallex RFID reader/writer

Hi all! I have just started using arduino and for my first project I'm trying to use my already existing Indala rfid card as a key for my computer.

In the beginning of this project I encounter a problem of reading the card. I've tried to search information about these Indala cards but I haven't found enough.

Does anyone know why the code(s) provided in the playground for this reader/writer doesn't read my card? I know it is for either EM4100 or EM4x50 but how can I solve what type is my card and how does these two exampels different from each other?