I have the same problem with Poloniex. I contacted my Gunbot reseller and he told me You are only allowed one account per exchange, unless you purchase multiple Gunbot licenses.
Older versions did seem to allow it, but I am using Gunbot v8.03.
it may have been a fluke, but Gunbot did run for me for several hours, making several trades before putting this message in the out.txt file:
[
The API key you provided is not from your POLONIEX account!!! Please use an API key from the same account of your MasterKey!
]
(note that there are multiple out.txt files in a fresh install of gunbot.)