Do you mean it is not available when you mouse over the My eBay scroll-down menu at the top of the page? Is it not available at the left under Lists on the left side when you click on the My eBay?
Or do you mean that you tried to add something to your Watch list today and it was not possible? In that case I would guess it is 'full', and you can make room by creating other lists for 'like' items. If you were, say, looking for skateboards and watching 62, you could put all those into their own list and make 62 spaces in the Watch list.
If, however, it is the first scenario, well then, ya got me. 🙂
