Setting your domain at Afternic is easy. And, a lot of domain investors are well-familiar with those tasks. First of all, you add a domain to your portfolio with the price you to sell for. And, once it’s done you need to confirm the listing by clicking the approved domain at the Afternic email link sent by your registrar.
If all is well and the setting has been done accordingly then your domain name should look like this:

Observe that the status shows the domain name is listed. And, most importantly the Fast transfer option is Yes(Active) and the domain has the buy now price along with floor and minium offer.
So, if the fast transfer is not active then you need to make sure it’s active by contacting your domain registrar. The fast transfer is generally enabled for participating domain registrars such as Godaddy, Epik, Dynadot, Etc. Also, your domain should not have the registry lock enabled – generally the 60 days lock.
I have found so many of my promo-based domain names not having fast transfer enabled. And, I am now working on this to correct it soon.