You may be trying too hard to achieve a lucid dream. I don't believe its easy to become lucid when you are frustrated about not getting lucid. Don't try the next few days, this could help you get a lucid dream. Also, if you expect to have an ld, you will, at least that worked for me on my fourth day.

You could also take a cold shower at 5 am or so, but I don't know how desperate you are.

Good luck.