Failed to connect to Anki

[MariZo-chan]

It seems that the Add-On Anki Connect (Anki-Melon) doesn't connect to an already opened Anki (see pic).
What could possibly go wrong?

1.The Add-on is installed to firefox,
2.The Add-on is installed to Anki
3. Anki is running
4.Yomichan is installed as an Ann-on to Firefox too, configured properly.
5.As soon as the problem seemd to continue, I thought that could be a little unspottable bug in the Anki itself. So I even changed my account in Anki to the new one and reinstalled everything, so that's a fresh start.

Many thanks in advance.
MariZo-chan