Effective ingredients missing or their concentration is too low.
Moisturizing
What does the product description say?
Does not contain the most effective ingredients for moisturization. The humectants
(glucose) can help attract water to the upper
layer of the skin. Keep in mind though that this product lacks emollients that can reduce the moisture loss over
time.
You might want to use a separate product emollients and occlusives like dimethicone, oils, or butters on top.