Also, keep in mind that it can take a few months of testing to notice a pattern. You may want to start testing a few days before what is recommended on the test through a few days after...or until you do notice a positive. Many women do not ovulate within the norm, and being off by just a day can make all the difference.
Be sure that you follow the directions carefully as well.
I second the recommendation of "Taking Charge of Your Fertility"...excellent resource when trying to conceive.
May I ask how long you have been trying to become pregnant and how long you have been testing? What has changed since you tried IVF?