Hi,
Sorry, the current demo (based on beta 2.57) available to the public doesnt support Kepler cards. It says that on the download page. This is why it wont run and you get that error.
However as I said the recent betas available to licensed customers do.
Also the Kepler Octane builds are for drivers with cuda 4.2 and higher whereas the demo you have is for drivers with cuda 4.0
So there are incompatibility issues.
You will have to wait a little while longer for some bugs to be worked out of the next release and then it will go live and the demo will be updated as well.
I assure you Octane is working well with Kepler cards in forum testing.
Do not needlessly upset yourself. Patience is a virtue, so they say.
In the meantime please feel free to ask any questions you have and some kind forum user will be probably be only too happy to answer them for you.
Please note though that once the beta phase is over soon the price of Octane will very likely rise from 99 euro to 199 euro.
All I can say is that many many people (over 4000) have taken the plunge and become Octane customers and not regretted it. Kepler users included.
HTH