Raspberry pi motion 4.7.0 tls ssl

I have successfully installed motion 4.7.0 on my rpi.I have given it a random port number and can see the picture locally on http://192.168.1.yyyy:xxx/I believe with this version (indeed since 4.4.1) it's possible to make it secure and therefore https://192.168.1.yyy:xxx/

I have created the certificates using openssl and put the following lines in /etc/motion/motion.conf

stream_tls onwebcontrol_tls onwebcontrol_key /usr/etc/motion/motion.keywebcontrol_cert /usr/etc/motion/motion.crt

However this does not work. Any ideas?

Many thanks for your help.