The disc may just need finalising.
Unless you have selected to finalise the disc most HDD/DVD recorders do not do this as default. This will allow you to add further recordings until the disc is full once finalised you can not add to the disc.
Samsung Galaxy S8 review
1995-2015: How technology has changed the world in 20 years
This poetic animation about monsters is illustrated in a Van Gogh painterly style
Apple predictions 2017
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.