C# Marshal.GetActiveObject("PowerPoint.Application") Error

I'm working on a tool to get running power point program and control it so i used this code to get reference of running program.

 var pptApplication = Marshal.GetActiveObject("PowerPoint.Application")

But it throws this erorr

Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE))

I noticed that was happening because my app was running as administrator but power point wasn't and when i run my app as normal it works, but i need it as administrator

Excuse me for my bad English.