[Box Backup] How to Ignore file backup?

[o omida parasita]

Hello,
I've set up box backup to backup my files
Now I have the following problem:
I receive this error by mail everytime when the following happens:
May 15 06:39:29 secure1 bbackupd[6503]: Backup object failed, error
when reading /opt/nagios/instances/jobmedia/var/nagios.tmpFgvklz

Can please somebody tell me how to setup ExcludeFilesRegex so it does
not try to backup files that match this pattern: nagios.tmp*

I tried ExcludeFilesRegex =3D nagios.tmp* but it does not work

Please help
thank you