When specifying the ceiling grid tile location for the ElumTools Layout Assistant, it is a requirement that the active Ceiling Plan have the Revit "Work-Plane" parameter set.  If the active view does not have a Work Plane specified, you will receive the error below when attempting to select the ceiling tiles.  You can fix this using the Revit "Set Work Plane" command.


Set the View Work Plane.

Error Message

 “Unable to complete ceiling grid selection.
Autodesk.Revit.Exceptions.InvalidOperationException: No work plane set in current view.
   à Autodesk.Revit.UI.Selection.Selection.PickPoint(ObjectSnapTypes snapSettings, String statusPrompt, Boolean bApplySnapSetting)
   à Autodesk.Revit.UI.Selection.Selection.PickPoint(String statusPrompt)
   à ElumTools.SelectionExtensions.SelectCeilingGrid(UIDocument doc)
ElumTools 2018 Release 5 (2018.5.0.3)
C:\Program Files\Autodesk\Revit2018\Revit 2018\RevitAPIUI.dll”