using a missing directive and assembly reference

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Runtime.InteropServices;
using webcam_capture;

namespace CSharpWebCam
{
    class WebCam
    {
       
        private  WebCamCapture webcam;
        private System.Windows.Forms.PictureBox _FrameImage;
        private int FrameNumber = 30;
        public void InitializeWebCam(ref System.Windows.Forms.PictureBox ImageControl)
        {
            webcam = new WebCamCapture();
            webcam.FrameNumber = ((ulong)(0ul));
            webcam.TimeToCapture_milliseconds = FrameNumber;
            webcam.ImageCaptured += new WebCamCapture.WebCamEventHandler(webcam_ImageCaptured);
            _FrameImage = ImageControl;
        }

        void webcam_ImageCaptured(object source,WebCam_Capture.WebcamEventArgs e)
        {
            _FrameImage.Image = e.WebCamImage;
        }

        public void Start()
        {
            webcam.TimeToCapture_milliseconds = FrameNumber;
            webcam.Start(0);
        }

        public void Stop()
        {
            webcam.Stop();
        }

        public void Continue()
        {
            // change the capture time frame
            webcam.TimeToCapture_milliseconds = FrameNumber;

            // resume the video capture from the stop
            webcam.Start(this.webcam.FrameNumber);
        }

        public void ResolutionSetting()
        {
            webcam.Config();
        }

        public void AdvanceSetting()
        {
            webcam.Config2();
        }


        internal void InitializeWebCam(System.Windows.Forms.PictureBox imgCam)
        {
            throw new NotImplementedException();
        }
    }
}