NullReferenceException after initialize the NotesSession

Greetings to all,

I am very new the Notes/Domino world and get quite frustrated about this.

Our application is accessing the Notes from the com object, but the com object throw this NullReferenceException from certain machines, not all of them. The client machine has 6.5 installed (upgraded from 5.x).

I am able to reproduce the behavior from my dev machine once, get the similar result to the following post

http://www-10.lotus.com/ldd/46dom.nsf/DateAllThreadedweb/f2fdcfcf602a06e98525717200005801?OpenDocument

I suspect it is because the interop.domino.dll is generated from Notes 7. So I regenerate it using the R6.5 I installed, it works. Since then, I won’t be able to reproduce this on my dev machine.

Because the client machines have different version of Notes insatlled, so I generate the interop.domino.dll from R.6.0. and rebuilt the app and send to client machines. The application still does not work on some client machines.

I still suspect that the interop.domino.dll make difference somehow, but I can not try match everything. Are there any other suggestions?

Our application will register “nlsxbe.dll” if it is not registered, so that won’t be a problem.

Thanks a million.