Hello and welcome to Android Forums! Hopefully I'll be able to answer your question or point you in the right direction.
Many of the call recording apps are finicky and do not like to work as advertised. What I would recommend doing, if possible, is wipe the cache and data for that app, then try deleting the app and reinstalling it. If that does not work I would try one of the many 3rd party apps available on Google Play. I'm sure that you will find one that works for you.
If you have any more questions regarding your device I invite you to join Android Forums and explore the section for your device. You may not only find answers to other questions you might have, you may also learn new things about your device.
WB7