Mine is a Draeger, they mess up too. I’m convinced that the technology needs to improve before they’re really ready for commercial use. The first time was because the mouth piece was defective. The second time was because I didn’t blow in time for the retest. The third time it was because I didn’t wait long enough after using mouthwash – that was my fault. Now they’ve set new parameters and it takes me 5 – 6 times before I can get the timing right and start the car. Can’t wait to find out what happens next!