Application Manager found a 0.2.9 version in extras, but the 0.3.0 is installed on your device, so it think that there is no need to display previous version, as you already have the last.

Now at this time there is two choice :

1) Using the last published in extras : by removing the current version of mcalendar and installing the previous.
2) Using the UNSTABLE AND UNTESTED new version 0.3.1 in extras-devel.

I recommend you to choose the first option, as the last version should fix the problem of the 0.3.0, but it s not tested, and you need something more stable.

Best regards