Have you placed the field on the screen and checked that it is enabled in the field configuration?
It's helpful that you've created releases, but even if you had not, you would still see the affects version field if it was valid for the project/issue type.
Check over https://confluence.atlassian.com/display/JIRA/Configuring+Fields+and+Screens for more detail.
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG