Problem on launching an Virtual Class From Saba Learning

Hi,

I having a problem on Centra which display a message like this "No servers are available to host this event. Please try again later."When i click attend using one of the learners ID, it display a message above. I check the Saba Connector error log, there nothing error show up. All the classes and users are created on Centra which i check it through using admin on Centra.Before this, I had test successful with all these Virtual Class between Saba Learning and Centra, but this time i really don't know what's wrong is happening.Anyone can help?

Any help will be apprecited.

I didn't find the right solution from the Internet.

References:
http://www.sabausers.org/forums/viewtopic.php?t=929
<a href="https://blog.advids.co/20-bitcoin-and-cryptocurrency-animation-explainer-video-examples/">Bitcoin Animation Video</a>

Thank you.