You are aiming for any level of ketones. If you only get to Trace, the palest pink, that IS success and you could lose well and NEVER get to the dark pink or purples.

If you are on the middle one, you are doing just fine and will lose well. Those stix are pretty cheap because they aren't all that accurate. Depending on their expiry date or how long they have been opened, the chemical that reacts with ketones may have become less reactive. So ANY change is success.