Changes in the language file dbem-de_DE.mo don′t show in fronted

Hi folks,
I wanted to change a phrase in my german language file dbem-de_DE.mo because it was rather bad translated. It belongs to the plugin events manager. I downloaded the file, changed the phrase – saved and uploaded it again in the same directory.
Even after deleting the cache in all my browsers there is still only the old phrase showing, although I also checked if the file on the ftp is the updated one.

As this did not work, I tried the CodeStyling Localization Plugin. I found the phrase and it shows the new one I already changed before with text-editor.

Can you please help me, what could be the problem…how can I make it show the corrected phrase?

Here is the link to the site: https://www.kds-wiesbaden.de/ags/natur-ag/ it′s the last sentence in the content area: >Buchungen sind für diese Veranstaltung geschlossen.<

Thanks in advance
Lucie