[Plugin: Tweetily – Tweet Your Posts Automatically!] Authorizes on one site, but not another

Thanks for this very handy plugin.
It installed fine on one of my sites. I was able to login with Twitter, and it then added it to my list of authorized apps. All works well.
But on another site I am not able to complete the login process. It brings up the Twitter app authorization page; I authorize it, but then it can’t return to the blog. The URL appears which returns to Tweetily, and it has auth details in the URL. But the page is blank. Twitter shows the app as authorized but the plugin does not think it is authorized.

Both sites use WP 3.4.1

Any ideas?

Thank you…

https://www.ads-software.com/extend/plugins/tweetily-tweet-wordpress-posts-automatically/