The search on our homepage is CrossSearch. It's good at finding results from a huge range of sources but it's not the best way to find out definitively if we have something or not.
Use our catalogue - http://opac.library.usyd.edu.au/ for that - title or author search is best.
If we don't have your title, or works by your author, "Your entry ... was not found. Search as keywords" appears where your title / author should have been in the alphabetic list, eg:
Click Search as keywords to double-check with an advanced search.
Click the green Bonus icon beside it to see if you can get the book from another Bonus library.