I've had three working ones that never had issues.Check for leaks, or could be that the reagent and sample isn’t mixing correctly. I’ve also had three tridents and got rid off mine when they sent me a third one. All replacements were brand new since I was within the first year. Keep in mind that this all happened within 4-5 months. The first two gave me the error for test B. Customer service is great but be prepared to take a whole video which can last 45 minutes with the cover off to see what the components are doing, then upload to YouTube and send them the link if you cant figure out what’s going on. I loved my trident when it worked but for the price tag and reagents you need to buy isn’t worth it. Specially when you count on it to monitor very important perameters. I’ll just wait to get another trident once they fixed all these issues.