Good luck.. I am agreement with other comments here.. If nothing happens soon then change agents and get a fresh approach.. I had a similar problem and found when I visited the unit that it needed a definite spruce plus the site nextdoor had turned into a major development site. Sometimes you have to bite the bullet and drop the rent just to get some income coming in. Have you had a frank discussion with the agent about the state of the unit and the curtains carpet, smells etc. plus ask what is going on in the area/building and has it become undesirable for some reason? (I assume you arent local to inspect it yourself)
  I hope you get a tenant soon. I also tried offering the first week rent free, but in the end someone who applied for the unit upstairs from mine and missed out took mine for $10 a week less than I was asking, but now he's been there 6 months and the development should be finished soon.