Permissions, most likely. Also, the remote machine that you're attempting to execute on, is it logged in with an active user session and an available desktop? If not, you can't run tests... and I think that TestComplete/TestExecute when attempted to run without that will return an error condition.
Yes, remote machine is logged in with an active user session and an available desktop.
What kind of permissions should be changed? On what side - Spira RemoteLaunch or TestComlete\TestExecute?
Is the RemoteLaunch configured to use that logged in session? See, I've never used Spira, so I don't know... I know what TestComplete and TestExecute require. They need to have an active, interactive desktop session. So, if you're RemoteLaunch is using some other session other than the logged in one, you might problems.
As for permissions, again, not sure what is needed to access the API... you might need local admin permissions. If nothing else, the remote launch needs to launch the tests within the existing logged in session and with at least the same user permissions if not elevated to administrator.
