1. The mobile phone system version does not meet the requirements.

2. Meng OL's signature is wrong.

For the above two points, you can:

1. Make sure your mobile phone is above Android 2.2.x

2. Uninstall the installed Dream OL and reinstall it.

I hope my answer can solve your question, and your support is the driving force for our progress ~4399 is more exciting with you!