Notes Sessions Vs Lotus Session COM API Issues

I maintain a fairly large application which does a lot of talking with Lotus Notes. Recently in the last couple of months, some users have been having problem connecting to the Lotus Notes Session, I use the following code to get the session

Set Session = CreateObject("Notes.NotesSession")

This error seems to be popping up only for a certain number of users. I created a sample app with the following line

Set Session = CreateObject("Lotus.NotesSession")

And开发者_StackOverflow the above line works for some reason. The user says there was some issue installing notes but has been rectified after a re-installation. Why are there two class names for the same object and why is one working an other one not working.

Any ideas on how to resolve these API issues?

This documentation on IBM's site mentions that Notes.NotesSession is OLE based,

After installing release 5.0.2b, you will see in the operating system registry a class named Lotus.NotesSession, as shown below. This is the root of the Domino COM classes. Still present are Notes.NotesSession and Notes.NotesUIWorkspace which are the OLE roots

I don't know specifically why the OLE classes are failing where the COM classes do not, but given that OLE is two decades old now, I would stick with Lotus.NotesSession

Not much to go on, but I'd throw ProcMon at it and see what registry keys and files are being hit when you request this object.

The Notes-Name and password still have to be 'current' for the login used. If the account has expired or requires recertification, access may be blocked?