Have you set up your account to sell?

If yes, then ebay must have given you some reason for not being able to list.  What does the message say?

I think it would be a good idea to have a chat with eBay support to find out what the problem here.

Link to selling chat page:

https://www.ebay.com.au/help/startchat_click?topicId=4105&fromIssueId=true&l2Name=Creating%20a%20lis...