The 15-day delay in menstruation test is not pregnant may be the results of the test paper is not allowed, may also be the menstrual disorders. 1. Inaccurate test strips: This situation may be caused by the quality of the test strips or improper operation methods, it is recommended to buy a few more test strips, according to the instructions and test again, the best way to determine the best way is to go to the hospital to take a blood test for HCG and ultrasound, which is the most accurate. 2. Menstrual disorders: If you have delayed menstruation only once in a while, it may be caused by poor mood, poor sleep, work stress and other reasons. This situation does not need to be nervous, you can follow the doctor’s instructions to use progesterone and other drugs to promote menstruation. If menstruation is often delayed, it may be caused by endocrine disorders, it is recommended to go to a specialized hospital to do a sex hormone test to clarify the cause. When this happens, it is recommended to consult a doctor in time.