Can't get it to work

Hi,

after using this plugin, I stopped using it for a while and now wanted to reactivate it. Unfortunately, I seem to be unable to do so.
I have the lasted plugin version installed, tripped-checked that my twitter keys are correct, but when I click the “ping twitter” button, nothing happens. I played around with some settings (e.g. daily/weekly digest etc.), but without success.

Thanks!

https://wordpress.org/plugins/twitter-digest/