2.2.317.0
System.NullReferenceException: Object reference not set to an instance of an object.
at Owen.Visualization.Helper.VariableReferenceFromCon trolElement.GetPath()
at ProgramRelayFBD.Presenters.VariableReferenceCollec torPresenter.<>c.<GetListBoxItems>b__10_0(BaseRefe renceToVariableDescriptor place)
at System.Linq.Enumerable.SelectListIterator`2.ToArra y()
at ProgramRelayFBD.Presenters.VariableReferenceCollec torPresenter.GetListBoxItems()
at ProgramRelayFBD.Views.VariableReferenceCollectorVi ew..ctor(VariableReferenceCollectorPresenter presenter, Boolean allowEdit)
at ProgramRelayFBD.InfrastructureLayer.ShowVariableRe ferencesService.Show(IVariableDescriptor variableInfo, String displayedText, IWin32Window owner, Boolean allowEdit, Func`2 referenceFilter)
at ProgramRelayFBD.InfrastructureLayer.ShowVariableRe ferencesService.Edit(IVariableDescriptor variableInfo, String displayedText, IWin32Window owner, Func`2 referenceFilter)
at ProgramRelayFBD.ManagerVariablesCommandFactory.Del eteVariable(DrawingDocument document, IVariablesTablePage page, BaseVariablesController variablesController, IVariableReferenceService variableReferenceService)
at ProgramRelayFBD.ManagerVariablesCommandFactory.<>c __DisplayClass1_0.<GetDeleteCommand>b__0(Object o, CommandEventArgs args)
at Nevron.UI.WinForm.Controls.NCommand.OnClick()
at Nevron.UI.WinForm.Controls.NCommand.PerformClick()
at ProgramRelayFBD.PresentationLayer.VariablesManager Form.ProcessCmdKey(Message& msg, Keys keyData)
at System.Windows.Forms.ContainerControl.ProcessCmdKe y(Message& msg, Keys keyData)
at System.Windows.Forms.Control.PreProcessMessage(Mes sage& msg)
at System.Windows.Forms.Control.PreProcessControlMess ageInternal(Control target, Message& msg)
at System.Windows.Forms.Application.ThreadContext.Pre TranslateMessage(MSG& msg)