Email notifications are not going out.

When i first installed Course Press, the version was 1.2.1.4 and now the version running is 1.2.1.8.

The email notification was working fine with the prior version but now it does not work, i tried various trigger points like: Inviting student/Instructor from (WP->Users->Add New, Course Press Pro->Student/Instructor->Add New), Create account from login window. But it doesnot send the Inviation/notification out.

Could you please help me with this issue. Thanks so much!