Unexpected error JTAG server code 35

I have a single device in the JTAG chain - EPM540T100.

Quartus II with USB byteblaster correctly scans this device.

When I try to program it, I get "Unexpected error in JTAG server -- error code 35". I have scope-probed pins 1,3,5,9 -- and activity seems normal, but not sure if it is exactly.

Can anyone tell me what error code 35 is? Why have an error code with no way to look it up? Thanks!

Scope probes were attached to the JTAG connector (USB blaster rev C).

The JTAG connector here is about 8 inches from the EPM570, and goes thru a 10-pin flex cable (two connectors) of about 3" long.

scope plots:

- jtag-scan.pdf = TCK + TMS doing JTAG chain integrity test

- jtag-program_TCK_TMS.pdf = TCK + TMS while trying to program device

- jtag-program_TCK_TDO.pdf = TCK + TDO while trying to program device