HELP!!!! Error when trying to import normals and spec maps

THis is the message i get
mind you im am extremely new to this. im trying to make a neon light using SimmerKate's video 


\The Sims 4 Studio - Version 3.1.5.8

System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object.

at S4Studio.ViewModels.Warehouse.WarehousePackageViewModel.ImportResource(WarehouseResourceViewModelBase existing, String f)

at S4Studio.ViewModels.Warehouse.WarehousePackageViewModel.<>c__DisplayClass45_0.<ExecuteImportResourceCommand>b__0()

at System.Threading.Tasks.Task.InnerInvoke()

at System.Threading.Tasks.Task.Execute()

--- End of inner exception stack trace ---

---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object.

at S4Studio.ViewModels.Warehouse.WarehousePackageViewModel.ImportResource(WarehouseResourceViewModelBase existing, String f)

at S4Studio.ViewModels.Warehouse.WarehousePackageViewModel.<>c__DisplayClass45_0.<ExecuteImportResourceCommand>b__0()

at System.Threading.Tasks.Task.InnerInvoke()

at System.Threading.Tasks.Task.Execute()<---