Please kindly expose the covers under the fluorescent lamp(Or other light sources, sunlight, LED light etc.)about 0.1-2.0M,at least 20 minutes(The more absorption time, the longer glowing time, If the absorption time is short (about 1 minute), it will also glow in the dark, but Glowing time will be shorter.), needs to absorb enough fluorescent energy before glowing. Verify that there is no ambient light source in the dark environment when the test glowing.