Search results are not sorted or ranked, because the search engine did not have enough information on which to rank the results. You will need to refine your search: use more keywords or clues.
Search results are generally ranked and then sorted, so the most relevant search results are displayed first. The RMIT web site search engine has a threshold of 1500 search results for sorting. It is not efficient to sort more than 1500 records, given inadequate search terms on which to rank the results.
More information: Search results