You have to post the error
There are issues with the beta (that's why it's beta. You upgraded to the newer version - from what to what? We need some more information
You can also add on this line:
http://github.com/nshahzad/phpVMS/blob/master/admin/modules/MassMailer/MassMailer.php#L91
if($pilot->active == '0') { continue; }
That will skip adding inactive pilots, no matter the group. Add it before that echo
You have to use Firefox and look at the error console. It's caused by a Javascript error and shouldn't be too painful to fix, usually it's a missing include.
If you search, it's come up before plenty of times
Both airports have to be in the database, it should be somewhat correct. Is it way off?
It will always say 'enroute' since FSFK doesn't send any flight status
XAcars doesn't give a status message (that's why there's the "generic enroute", same for distance/time remain. I try to guess it but it seems like it isn't there. Do you have the start/dest airports entered into the admin panel properly?