Scanjet 4C and AVA-2902A Host Adapter

I have a scanner HP Scanjet 4C connected to a serve via a SCSI host adapter AVA-2902A. I have an internal device connected to the 50 pin internal connector (a zip drive) and the scanner to the external, there is no termination in the card and I have made the termination on the scanner. Once I try to scan using deskscan 2.9, the adf feeds but there is no pass to scan. What can I do???