Searches for "Washington" and "Washington, DC" found nothing for me. When I browse I see "District of Columbia", nobody actually calls it that.
Right now at least one keyword such as Java needs to be specified in order for the search to return results (assuming there are jobs with those keywords). Adding a location (you can have multiple cities and/or states) narrows your search down to jobs in those cities or states.
We may change the logic to return all the jobs if only a location is specified. This seems to be the confusing part. (We're analyzing job searches to improve them.)
Thanks for your feedback!