Skype for Business Voicemail Icon missing

Hello,

since some days my Voicemail Icon is missing.

This step doesn't work:

Exit Skype for Business and Outlook client.

Navigate to Users > username > AppData > Local > Microsoft > Office > 16.0 > Lync

Delete sip_profileName folder. 

Delete all files in Tracing folder. Do not delete the folder itself.

Login to Skype for Business again.

Any Idea?

Thanks + Regards