I took a look at your API key on our end, and it's showing that your program is still accessing the Constant Contact account successfully. I'm not sure how the code was created, but it sounds like this might be something within the code of the app that's stopping this posting...possibly due to the special characters in the title, but it could be a number of things.
I would test deleting the email from your site, to see if that allows the other emails to post. If it does, there may be something within the code that stops at those special characters. If it doesn't work, there may be some sort of limit in the code, or some sort of change that is affecting how the calls are handled.