It sounds a little bit strange. I don’t think the card reader has any problem
because is somehow a way of communication between the pc and the card.
It doesn’t maters what kind of file you are trying to transfer.
You have to copy the file in the specify directory that your mob tries to open it.
If this doesn’t work try to copy the file as .zip and rename it there as .jar
but only when you are using the card reader not on the mob