Can't connect to Smushit Server

I keep getting the following error message when I try to bulk smush my images:

Oh Snap! Seems like Smush Pro server is not reachable, you can try back in some time.

As far as I know, I don't have any cacheing plugins installed or CDN networks but I would like to use those in the near future.

1. Can this plugin work simultaneously with a CDN network and with cacheing plugins?
2. If yes, How can I fix my current problem?

Please let me know,