There are few things that could cause this issue:
Try the following:
1) The issue you mention with the path to the Notes.ini file (as per https://support.quest.com/Search/SolutionDetail.aspx?id=SOL25928). [You have already done some of this it seems but pay attention to the PATH statements]
2) Outlook has not been installed or ever run.
3) The location of the nnotes.dll is not included in the system PATH variable.
4) If using roaming profiles, the roaming profile drive is not added to the PATH system variable. For example, add the H:\Notes roaming profile mapped drive to the PATH System variable on the workstations.
5) An improperly registered Notes install (would require reinstall of Notes client). Make sure that you reboot the PC after uninstalling Notes; before you reinstall it.
Complete this troubleshooting guide to get to the bottom of your issue.
