K-9 Mail not working with Openkeychain

K-9 does not seem to find the installed Openkeychain app. OKC works fine and so does K-9 except for this problem. Both programs have been installed from F-Droid and are the the latest version. I am using a Moto G ("falcon") with ParanoidAndroid 4.6b5 without Gapps. APG used to work. Thanks in advance for any help.