If you are having trouble setting up your WiFi connection in Diamond/Pearl, or have questions concerning it, ask here.
Anything relating to connecting to the Global Trading Station should be asked here.
Make sure you detail your problem as fully as you can. Saying "I can't connect, help me" won't get you any help.
Nintendo Router Compatibility
Nintendo WiFi Tech Support
Pocket Gamer- WiFi Walkthrough
If it turns out we can't help you, try contacting Nintendo, your Router company, or your Computer company.