There are a few possible reasons why you can't smell the essential oils in your diffuser. First, the essential oils may have evaporated too quickly. If this is the case, you may need to add more drops of essential oil every few hours to maintain the desired scent. Second, the essential oils may not be diffusing properly. Ensure your diffuser is working correctly and the essential oils are being dispersed evenly throughout the space. Finally, the essential oils may need to be of better quality. If the essential oils are old or not stored properly, they may be more aromatic than they are.