The VBA COM line Set Visum = CreateObject('VISUM.VISUM.180') fails with the following error message: 'ActiveX component can't create object'.
The Python line Visum = VisumPy.helpers.CreateVisum(...) fails with an error message, containing at the end the string: 'Invalid class string'
The computer uses a 32 bit or 64 bit operation system.
PTV Visum needs to be registered again as COM server.
Until Visum 12 use an external tool in the start menu: Register Visum as COM server (again): Start -> All programs -> PTV Vision -> Visum -> Tools -> Register as COM server -> (Click right mouse button) -> Execute as Administrator.
Since Visum 11 an internal tool is available: - Visum 11-12.5: Extras -> Options -> (Working) Environment -> General -> Register as COM server. - Visum 13: Edit -> User Preferences -> Working environment -> Register as COM server. - Since Visum 14: Help -> Register as COM server.
Notes: - Make sure to start PTV Visum with administrator credentials. This procedure could be necessary again after the computer was rebooted. - Check in the Windows register, which class ID is currently registered.