Try the following actions:

• Check that your BlackBerry® device is connected to the wireless network.
• If the menu item for sending a message does not appear, verify that you have added an email address, a PIN or a phone number for your contact.
• If you created an email address or added an existing email address to your device using the email set-up screen in the Set-up application, check that you have received an activation message on your device from the BlackBerry® Internet Service. If you have not received an activation message (the message might take a short period of time to arrive), in the Set-up application, open the email set-up screen to send a service book to your device.
• If you have not received a registration message from the wireless network, register your device. On the Home screen or in a folder, click the Options icon. Click Advanced Options > Host Routing Table. Press the key > Register Now.
• Generate an encryption key.
• Verify that data service is turned on.
• Resend the message.