The reason why this signature is displayed incorrectly is that the signature format is incorrect, too long or too short, and the identity cannot be verified.

1. The signature format is incorrect: the reserved signature of mobile phone needs a specific format, such as font, size, color, etc. If it does not meet the requirements, it may be rejected.

2. Too long or too short: the signature has a certain character limit. If the number of characters exceeds the limit, or there are too few characters, it may be rejected.

3. Unable to verify identity: the provided signature cannot match or verify the identity information of the registered mobile phone number, and it will also be rejected.