Detect Sony RC-S380

Hii all

i have a task to read the sony felica card by using sony RC-S380 reader.

i've an issue with using sony reader. when i begin to try to read the value of a card, its all done and okey. but i just work for a few minuts. maybe just for 3 minuts. then after that, the reader cannot work normally. sometimes its give a wrong value or it cant detect the card,
can you all help me with that issues?

salam

anisa