Silicon ID problem with Nios kit

Hello all,

I have Nios Development kit with Cyclone FPGA 1C20. This kit has not been used much in our lab. I have been able to successfully program the EPCS4 on this board using AS programming mode. But when I try to program the FPGA directly using JTAG header, I get the error "Can't recognize Silicon ID for device". Is it that my byte blaster is having some problem? Can it be that the same byte blaster works for AS programming, but fails for JTAG. How can I check this?

regards,

rajesh