problem of cyclone 3 jtag, tdi pin id always low

hi all:

this something wrong with my ep3c16 fpga.jtag can't scan the divce. tdi pin is always low.between the fpga tdi pin and jtag connector, there is a 100R resis.the voltage of connector side is high level,but the fpga side is loe level.

if the chip is down?? this is the 3rd chip that same problem.