You probably get this message because you don’t have enough posts to fill both featured area and main post listing below.
Disable “Do not duplicate” option
Inside Theme options -> Category template you will find the option which prevents posts to appear twice on the same page. If this option is enabled, posts in featured area will be automatically excluded from the main listing below and that’s probably the reason for getting the message.
Disable “Featured area” entirely
You can also turn off featured area entirely for this category until you have more posts to display, or, reduce number of posts displayed in featured area.