Somehow I doubt the problem comes from XML::Twig. I have extracted the getAidTitle function and run it on test XML data... and it works fine, except of course I get a warning for your use of or "No title", which I guess used to be a croak "No title", and another one on the next line.

Do you also have the same problem if you replace the entire getAidTitle by a constant?

One last remark: you should use strict; at the top of your code, it would catch most typos in variable names.