If you have an author not sorting right it is usually an issue with the default sort specified for that author.
http://manual.calibre-ebook.com/faq....es-and-sorting
For most users it is going to be the case that an edit of the Author Sort column is required via the Manage Author(s) dropdown on the Tag browser screen and/or editing the author sort for the books in question. There are a range of permutations of that though depending on what your preferred sort/display order is, what your tweaks are set to etc. Just read the help section above and if you are still stuck with it post *all* of the details of the issue, attaching screenshots always helps.
Edit: of course theducks had the same thought at the same time...