C#: Error System.Runtime.InteropServices.COMException (0x800706BE)

I'm getting error like "System.Runtime.InteropServices.COMException (0x800706BE): The remote procedure call failed. (Exception from HRESULT: 0x800706BE)" while performing C# Excel.SaveAs(filepath). It works for few documents but for one document it's failing. I don't know what is wrong with the file, but the file is not corrupted. What might be wrong? Please suggest few answers.

Thanks in advance.