I notice in your screenshot that you're missing an equals sign in the middle of your connection string. I'm assuming it's an encrypted string, and probably is not able to be decrypted correctly. Does the connection work if you don't assign the string from the app.config file? I know C# has to escape some sequences in strings sometimes, and I wonder if this could be the problem here. You can also use an @ to indicate a string literal so that the string doesn't need to be escaped. But obviously this doesn't help much if you're trying to get it through your config file.
I dont get the first thing about the equals sign... But i have try to do it without the app.config, but still the same problem.