I do not have an issue with snapcreator --start-agent 9090 , this is working just fine and this how I have been testing the config and had not problems.
The issue is to start the SC Agent Service which is starting which is using scAgentService.exe , this is the problem programm. I can not even start it from the cmd to get some options to figure out whats going on.
ok the SCAgentService.exe which is started by the Service Manager is a small "wrapper" to start the snapcreator.exe written in .net. It is ecentially the interfave between the Windows Servive Manager and the snapcreator.exe.
After installing .net 3.5 the service started with no problems.