AutoCAD .NET :: Error In Document Object Creation

using System;
using System.Threading;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Runtime.InteropServices;
using Autodesk.AutoCAD.Interop.Common;
using Autodesk.AutoCAD.Interop;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.EditorInput;

[code]....

Working Environment:-

Visual Studio 2010AutoCAD 2011 C#
 
After run following error will occure

"An unhandled exception of type 'System.TypeLoadException' occurred in mscorlib.dll

Additional information: Method 'CopyTo' in type 'Autodesk.AutoCAD.ApplicationServices.DocumentCollection'

from assembly 'acmgd, Version=18.1.0.0, Culture=neutral, PublicKeyToken=null' does not have an implementation ."