Tips: The app locks on to lighting artifacts sometimes. Try to have uniform lighting, or illuminate from both sides to evenly light it.

To get accurate results, make sure you're looking straight-down, 90 degrees. The accuracy of this tool is theoretically 80%, but how you take the picture and how the egg is may affect the results. Data taken from this study.

If you're having trouble with this, check out the "live" version here. It might work better.