I think you have None swatch selected and then you are seeing "Create new swatch" button icon at the bottom of swatches panel greyed out. This option will however be enabled in Swatches Panel fly out menu. When create new swatch button is clicked and a swatch is selected, it creates a copy of it and that is the reason why it is greyed out since copy of None swatch cannot be created. Please let me know if your scenario is different from what I have stated.
It will be disabled with the Registration and [Paper] swatches selected as well...