IPhone 4 does not find any Wi-Fi?

I got the iPhone 4 today and it is not picking up any Wi-Fi signals. I know that it is not my internet router because the Wi-Fi on my parents' phones works and it also worked on my iPhone 3G earlier today before I got the 4. I have the Wi-Fi button on and the "ask to join networks" on as well, but even when I pull up an app or safari, it does not give me any suggestions. I have reset the network settings and I'm still having the same problem!
Has anyone else had this problem and how did you fix it?

Restart router

I would like to recommend you to buy 4glte router, no matter where, you can connect you Wi-Fi