If you are receiving an error message when trying to share photos wirelessly with another Nintendo DS, follow the steps below.
Make sure you’re in range of the other user, and that there’s nothing that could be blocking your connection. You should also check that you aren’t near any devices that could interfere with your wireless signal, such as microwaves, cordless phones, computers, etc.
If so, you may have to reset your wireless settings.
To reconnect your system to the internet, follow the advice from How do I connect my Nintendo DS to the internet?