I have a problem with programming BricsCAD with c# in visual

public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { BricscadApp.AcadApplication cadApp = new BricscadApp.AcadApplication();          cadApp = (BricscadApp.AcadApplication)System.Runtime.InteropServices.Marshal.GetActiveObject("BricscadApp.AcadApplication");         cadApp.Visible = true; BricscadApp.AcadDocument ThisDrawing = cadApp.ActiveDocument; Point2d asd = new Point2d(10, 20); Point2d asdf = new Point2d(25, 30);         cadApp.ActiveDocument.ModelSpace.AddLine(asd, asdf); } }