GSA SER and webshare.io API

Hi there,
I am using (better trying to use) rotating webshar.io proxies via API in SER.
I created in webshare a API key, in SER: – configure – add proxy – enter API (webshare).
I copied the key and pasted it – ok
Sometimes no proxy showed, sometimes the proxies are shown, but are all tested “not working date/time”.
As they are rotating it would be nice, that the Proxies are also rotating using the api, so I don*t have to (would have, if it would work) update them every 15 Minutes manually.
Can anyone help me with that. Is there anything basic I did wrong?
I contacted webshare support, but they could not help as they were “not familiar” with SER (although they advertised as SER Proxies…)
Thanks in advance and
best wishes
Chris