ok, this is strange - because the conditions set in android-info.txt inside the rom.zip file of htc's unlock actually should get you covered (assuming it is mainver 1.
in another thread
it was supposed that this problem might appear when a radio, newer than the one the RUU shipps with, is already present on the device.
you therefore might want to try downgrading/flashing radio version 7.13.35.05
first, then see if you can install the stock rom ruu and afterwards the bootloader unlock. otherwise i'd be out of suggestions :-/