Just delete the amounts etc in the boxes it is telling you to do and reenter the details again. on some it will then let me list..other times I have to do this a couple of times before it works.

When the above doesn't work: click on Save for later at the bottom of the 1st page and then go into the listing again under your Sell items it should then be Ok and the message will not reappear

Having to re enter a whole new listing is so frustrating. Hope this helps