Using Serilog with MvvmCross

I have this code in Setup.cs file

      protected override MvxLogProviderType GetDefaultLogProviderType() =>                                                  
                                                 MvxLogProviderType.Serilog;

      protected override IMvxLogProvider CreateLogProvider()
      {
          Log.Logger = new LoggerConfiguration()
            .MinimumLevel.Verbose()
            .WriteTo.Logger(config => config
                .MinimumLevel.Verbose()
                .WriteTo.File("C:\\log.txt"))
            .CreateLogger();
        return base.CreateLogProvider();
    }

In the ViewModel I have : private readonly IMvxLog _log initialized through IoC.

When I call _log.Error("Some error") nothing is written in log.txt file.