Hmmm,
i got an error in the log file of the scheme editor.
2018-05-17 12:54:40 <xxx><xxx><ACT> Load components from files
2018-05-17 12:54:40 <xxx><xxx><EXC> Error loading components from files:
System.NullReferenceException: Object reference not set to an instance of an object.
at Scada.Web.Plugins.PlgSchBasicCompSpec.Init()
at Scada.Scheme.CompManager.LoadCompFromFiles()