If the certificate expires, it will be easier to solve. Before installing the software, set the date of the mobile phone in advance. For example, today is July 24th, 2009. Please adjust the date of the mobile phone to June 65438+1 October 20091to see if it can be installed, or prompt that the certificate has expired, move the time forward to be installed, and then adjust it back to the normal time after installation, which will not affect the use of the software in the future. However, if the time is adjusted too early, you will be prompted that the certificate has not yet taken effect and you have to adjust it later. Many times you will encounter the problem of prompting that the certificate is wrong, and then you need to sign the software. There are also two certificates needed here, one is a mobile phone certificate and the other is a signature tool. Simply put, the mobile phone certificate is a specific certificate file sent to you by Saipan according to your mobile phone serial number, and you need to apply. Of course, the application is free. You can apply for free at Mobile Home, Saipan Forum and Zhongguancun Forum. A certificate is like an official seal, and software signing is the process of stamping the software and allowing it to be installed on your mobile phone. If you want to write in detail, I'll give you an address for reference: /use/symbian/ You can learn how to apply for a certificate, where to apply, how to download a signing tool and how to sign software.