0.0: Valid reading, meter does not detect ketones. Try reducing your carbs further and make sure to avoid hidden sugars and carbs. 

0.1 to 0.5: Your body is starting to produce trace amounts of ketones, but you are not in ketosis quite yet.

0.5 to 1.0: Nutritional ketosis starts. You may start seeing diet benefits and improved energy levels.

1.0 to 2.0: Optimal Nutritional Ketosis. This is the ideal target range for most people. Your body is burning fat for energy. Many people also experience optimal mental and physical performance at this level.

2.0 to 3.0: Post Exercise Ketosis. In this range, you will likely not notice any additional benefits or detriments compared to the previous 1.0 - 2.0 range.

3.0 to 5.0: Starvation or Fasting Ketosis. Maintaining these levels consistently should not be a long term goal for nutritional ketosis.

Above 5.0:  It is an unlikely reading to result from the keto diet alone without fasting or supplements. There may be an issue with your test strips. Try a new strip (preferably from a different vial) and contact support. Seek medical attention if you aren't feeling well.