The NOX pump bottle operates on a vacuum and you will need to give several pumps before the vacuum pump will be activated. Because the Activator and Serum are different viscosities so one side may “prime” first before the other side begins to dispense. This is normal with the consistency of the ingredients in the dual chambers and may require additional pumps before both fluids begin to dispense together. We have thoroughly tested the bottles to ensure that they would perform adequately. Again, this is normal with the consistency of the ingredients in the dual chambers and may require additional pumps before both fluids being to dispense together. We have added extra product to both chambers to account for this.