VS2015, build failed with error : SA1027: Csharp.Spacing: Tabs are not allowed. Use spaces instead

Question

I've tried every step as outlined in https://www.codeproject.com/Questions/786538/Error-SA-Tabs-are-not-allowed-Use-spaces-instead

• selection all of your code (CTRL+A), than Edit->Advanced->Untabify Selected Lines
• Tools->Options->Text Editor->C#->Tabs, change 'Keep tabs' to 'Insert Spaces'

I can't get rid of the error.

Below is the detailed error message. Please HELP.

Build FAILED.

   "C:\One\EngSys\Supportability\AzureDiagnosticServices\src\Diagnostics.HelloWorld\Diagnostics
   .HelloWorld.csproj" (default target) (1) ->
   "C:\One\EngSys\Supportability\AzureDiagnosticServices\src\Contracts\Contracts.csproj" (defau
   lt target) (3) ->
   (StyleCop target) ->
     C:\One\EngSys\Supportability\AzureDiagnosticServices\src\Contracts\Models\SymptomDirectory
   .cs(192,115,192,115): error : SA1027 : CSharp.Spacing : Tabs are not allowed. Use spaces ins
   tead. [C:\One\EngSys\Supportability\AzureDiagnosticServices\src\Contracts\Contracts.csproj]

0 Warning(s)
1 Error(s)