How come I can't bundle an instance from Amazon's AWS Management console?

When I select a running EC2 instance and click the "instance actions" pull-down, the option to bundle the image to an S3 bucket is grayed out. Why would this be?

See here: http://skitch.com/eoligarry/dnr7n/aws-management-console

I am signed up for S3开发者_Go百科, and this is not a windows instance.

Creating images (and also stopping/restarting) is only possible for EBS-based AMI instances, not for instance-store images, which boot from local and non-persistent storage. Bundling from the console is possible only for Windows-based machines that are instance-store instances (don't remember why, it's somehow related to the AMI-tools).