Graphviz. Ошибка "dot: can't open dot"

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;
using QuickGraph;
using QuickGraph.Graphviz;
using QuickGraph.Graphviz.Dot;
 
namespace GKS_Full_v1
{
    public class Graph
    {
        AdjacencyGraph<string, Edge<string>> graph = new AdjacencyGraph<string, Edge<string>>();
        public void Test()
        {
            graph.AddVertex("A");
            graph.AddVertex("B");
 
            graph.AddEdge(new Edge<string>("A", "B"));
 
            var graphViz = new GraphvizAlgorithm<string, Edge<string>>(graph, @".", GraphvizImageType.Gif);
            graphViz.FormatVertex += FormatVertex;
            graphViz.FormatEdge += FormatEdge;
            graphViz.Generate(new FileDotEngine(), "graph.dot");
        }
 
        private static void FormatVertex(object sender, FormatVertexEventArgs<string> e)
        {
            e.VertexFormatter.Label = e.Vertex;
            e.VertexFormatter.Shape = QuickGraph.Graphviz.Dot.GraphvizVertexShape.Box;
            e.VertexFormatter.StrokeColor = GraphvizColor.Black;
            e.VertexFormatter.Font = new GraphvizFont("Calibri", 11);
        }
 
        private static void FormatEdge(object sender, FormatEdgeEventArgs<string, Edge<string>> e)
        {
            e.EdgeFormatter.Head.Label = e.Edge.Target;
            e.EdgeFormatter.Tail.Label = e.Edge.Source;
            e.EdgeFormatter.Font = new GraphvizFont("Calibri", 8);
            e.EdgeFormatter.FontGraphvizColor = GraphvizColor.Black;
            e.EdgeFormatter.StrokeGraphvizColor = GraphvizColor.Black;
        }   
    }
 
    public sealed class FileDotEngine : IDotEngine
    {
        public string Run(GraphvizImageType imageType, string dot, string outputFileName)
        {
            string output = outputFileName;
            System.IO.File.WriteAllText(output, dot);
 
            Process process = new Process();
            process.StartInfo = new ProcessStartInfo("@"C:\Program Files (x86)\Graphviz2.38\bin\dot.exe"");
            process.StartInfo.Arguments = @"dot -Tgif graph.dot -o graph.png";
            process.Start();
 
            return output;
        }
    }
}