The number one reason you may be having an issue is a lack of adequate lighting on the LaunchPad area. Make sure to increase the lighting, and be careful to position the light in a way that it does not cast shadows across the LaunchPad area.
Also, please go through this checklist:
If you follow the steps listed above and the issue continues to occur, please contact us through this form with your device model number and a few pictures or a video of the issue occurring so we can better assist you:
Here are instructions to find which model / device you have:
iPads: open Settings > General > About
Fire tablets: open Settings > Device Options