What am I doing wrong?

from http://www.tazorac.com/how_to_use_taz_read.aspx
The website has the answers to all your questions.

How to start and stick with Tazorac
Think 1-2-3 once daily
1 Wash your face with warm, not hot, water and a mild cleanser. No astringents or alcohol-based products
2 Apply moisturizer before using Tazorac (tazarotene) Cream or Gel 0.1% to minimize drying and irritation by restoring the skin's protective barrier
3 Spread one pea-size drop of Tazorac over your entire face. Using more will not make your skin better faster and could cause irritation.

You will need to use Tazorac for 12 weeks.

* Your skin should start to improve after 4 weeks. During the first few weeks of treatment, even when the medicine is working, it may appear that your skin is getting worse. After that, you should be seeing improvement. Be a patient patient and stick with Tazorac as directed
* Go all 12 weeks. Studies on Tazorac Cream and Gel 0.1% show good results on most people at that point. Give the medicine time to work
* Protect your skin. Always use sunscreen and cover your face in cold, windy weather
* Be nice. Don't rub, scrub, pick, or pop pimples
* If you have any concerns during your treatment with Tazorac Cream or Gel 0.1%, contact your doctor.