Pregnancy test shows up not pregnant and then pregnant every other one?

First of all, why would you buy the Wal-mart brand? Nothing works from Wal-Mart. I once saw an outdated pregnancy test sitting on they're shelves that expired in 2010. You need EPT or Clearblue Easy. They are 99% accurate but there is that 1% chance they are wrong. Go to your doctor for accuracy. In the future if you can help it, don't by any products that are generic from Wal-Mart which is anything that says EQUATE. You get what you pay for there which is usually crap. Good Luck and I hope you get the answer your looking for!!