Shipping Service Not Found?
This error pops up when you're using Calculated Shipping as your shipping method. If you're using calculated shipping you must select shipping services to go with them based on weight. As seen in the photo below:
Priority Mail is a valid service, and eBay will use that service to calculate the shipping cost to the customer who buys the item. If you're doing free shipping, no services have to be selected because there isn't a calculation involved in them.
You can also go over shipping details in 'edit' and choose or even change services from your defaults. Once the errors are corrected the listing will properly push to eBay.