Note, if you are certain that the provided user credentials (Dexcom Share/Follow user name and password) are correct but GlucoGram is not able to establish a connection with the Dexcom Share server then please don't hesitate to contact me. It is possible that your Dexcom Share account is not on the default Dexcom Share server. In that case, I might be able to help you.
It is easy to submit a bug report. Open the GlucoGram menu and click on the drop-down icon and select "History Log" and then "Share...". This will create an email automatically. Don't forget to add any additional information that describe the issue before you send the email.