Is there already a different IS-IS instance running on your router?
Ordinarily, IS-IS is configured in router isis mode without any instance name. You, however, are configuring your IS-IS in router isis Name mode. Do you have any particular need to configure the IS-IS instance using the Name tag? Can you try configuring it without the Name argument?
Interesting. After googling for this message, I got inconclusive results.
As a workaround, the only recommendation I can currently give it to use a different SystemID in the router iso-igrp process and a different SystemID in the router isis process. Can you try this out?
Some posts hint on the fact that this may be related to IS-IS Multiarea support which is not available in your IOS version. The latest IOS versions for 2911 that supported IS-IS Multiarea are 15.1(3)T or 15.1(4)M3. Perhaps you could try to downgrade your IOS to one of these versions and see if it helped.