The command is not saved in crontab, what should I do?

Question

Task Schedulers

I'll explain the situation.

I write the crontab -e command, the configuration file opens.
At the end of the file I add the line:
* * * * * /root/backup.sh
and save it.
Then I write the /crontab -l command in the console. Writes "no crontab for root".
What to do? The editor used is nano.

Answer 1

there must be an empty line at the end of the crontab file