In a 40K gallon pool, 9 lbs. of stabilizer will only give you a reading of about 28ppm which isn't really gonna show up in a test. The minimum that can show is usually around 30. I think you just need to add more CYA. Add about 4 more lbs and then retest it in about a week and report your level. That should give you a level that can be detected and it should read about 40-45ppm of CYA.