Subdomain Issues?

Hello, I wanted to test this plugin and have created two new WP installs. My mastersite has the address http://dev.domain.com. My second site has a domain http://shop.domain.com. When I try to sync from the second site, I get the 'There was a connection problem. Please check the URL and Key of the Master site.' error.

I have checked my logs but there were no errors. I have tried deactivate/activating the problem but still could not sync. Can someone please help.

Thanks