Consider to double check for proper termination of the SCSI bus. Most likely the card reader will have a jumper to enable or disable internal termination, usually near the SCSI ID jumper block. Make sure internal termination is off if you use it in an external enclosure and use an external termination resistance. Make sure it is on if the device is located at the end of a cable, like internally connected to the IDC connector at the end of the SCSI chain.