First, check that you have either a cellular or Wi-Fi connection. ECG data cannot be shared if you do not have this connection.
If printing, ensure that the printer is setup properly. In order to print from the AliveECG app, you will need a wireless printer. Please reference this link for a list of AirPrint printers that would work.
If you are sending data to the AliveCor server, ensure that the AliveCor username and password you are using in the app is the same username and password you are using to access the data on the AliveCor website. You can adjust your username and password in the app under Settings.