'Trying to connect' & then at 'Disconnected'

With great difficulty I installed 365. somehow added my account too in the outlook 365. 

Now that the account is added - it still at 'Trying to connect' & then at 'Disconnected' state. 

I cannot understand that every other app of office 365 Word Excel etc....works just fine with the same login credential except Outlook...

can some one guide me what shall be checked further in this regards. ..