LH7A400 IDCODE instruction kaput

I've been trying for several days now to get jtag-0.6 to correctly detect the IDCODE on an LH7A400. I have been able to use JtagIO to read the ID code on this and other identical boards without difficulties.
Here is some output:

jtag> cable parallel 0x378 WIGGLER
Initializing Macraigor Wiggler JTAG Cable on parallel port at 0x378
jtag> detect
IR length: 4
Chain length: 1
Device Id: 0
chain.c(110) Part 0 without active instruction
chain.c(133) Part 0 without active instruction
chain.c(110) Part 0 without active instruction
jtag>

The device ID is obviously wrong. I'm not sure at what point it is failing, although I have been through a bunch of the code with gdb. Any assistance you could provide would be welcome. (I'd be glad to work on the software too, but I am puzzled with regard to this problem.)

Thanks!