Don't focus on the ketostix. There's a big split in the low-carb community about whether ketosis is even necessary for weight loss. Ketosis simply is the byproduct of incomplete fat burning. The more efficient your body gets at burning fat, the fewer ketones you excrete. Also, if you're drinking as much water as you ought to, that will dilute the concentration of ketones, making it appear as if you're not in heavy ketosis during a single test. Most of us who've lost weight have come to gauge our ketosis by our bad breath (fixable by drinking enough water, and taking parsley oil capsules) and the metallic taste in our mouths.