Send Email Sample using MSOutlook failed to initialize

I tried the MSOutlook sample, I got exception "Unable to initialize MS Outlook". 

My register key for 'HKEY_CLASSES_ROOT\Outlook.Application\CurVer' has 'Default'='Outlook.Application.15'

I have changed the script to 'MsOutlook = Sys.OleObject("Outlook.Application.15");' in function 'InitializeOutlook()'