Please be sure that you are in an area with good mobile reception, and that your phone number is capable of sending and receiving SMS (if possible, we suggest sending and receiving an SMS to/from a friend).
If you are sure there is no problem with your reception or account, then please restart your phone and try again after 15 minutes. Sometimes the telcos with whom Coda works do have technical problems with their SMS deliver, so please check the "Service Announcements" section of this website as well: we will list any known ongoing technical problems on that page. Typically these problems are solved within 1-2 hours, so it's always a good idea to try your purchase again later.
For further assistance, please contact our customer support through this form. We apologise for any inconvenience.