Использование delegate функций из библиотек

namespace SoundLib
{
 public class Sound : IDisposable
    {
        public delegate void WaveCallbackProc(IntPtr hwi, WimMessageType uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2);
....
        public static int StartInAudioDevice(int DeviceID, WaveCallbackProc InCallBackFun)
        {
            if (waveInOpen(ref hWaveIn, DeviceID, ref waveFormat, Marshal.GetFunctionPointerForDelegate(InCallBackFun), IntPtr.Zero, CALLBACK_FUNCTION) != MMSYSERR_NOERROR)
                return -1; // Debugger.Break();
.....
        }
.....
    }
}

using SoundLib;
 
Sound.WaveCallbackProc InFunCallBack = CallBackIn;      <- Ошибка
 
и соответственно 
 
        Sound.StartInAudioDevice(InAudioDeviceID,InFunCallBack); 
....
        public static void CallBackIn(IntPtr hwi, WimMessageType uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2)
{
....
}

   public static void InAudioCallBackFun(IntPtr hwi, WimMessageType uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2)
        {
            return;
        }

        public delegate void WaveCallbackProc(IntPtr hwi, WimMessageType uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2);
        public static WaveCallbackProc waveInCallback;
....
        public static int StartInAudioDevice(int DeviceID)
        {
            waveInCallback = InAudioCallBackFunction;
 
            if (waveInOpen(ref hWaveIn, DeviceID, ref waveFormat, Marshal.GetFunctionPointerForDelegate(waveInCallback), IntPtr.Zero, CALLBACK_FUNCTION) != MMSYSERR_NOERROR)
                return -1; // Debugger.Break();
        }
 
        public static void InAudioCallBackFunction(IntPtr hwi, WimMessageType uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2)
        {
.....
        }

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using Microsoft.Office.Tools.Word;
 
namespace WordApplication
{
 
    public partial class frmMain : Form
    {
        private Microsoft.Office.Tools.Word.Controls.RichTextBox rtb;
 
        public frmMain()
        {
            InitializeComponent();
 
            Sound.WaveCallbackProc callback = InAudioCallBackFun;
        }
 
        public static void InAudioCallBackFun(IntPtr hwi, int uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2)
        {
            return;
        }
    }
 
 
    public class Sound : IDisposable {
        public delegate void WaveCallbackProc(IntPtr hwi, int uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2);
        public void Dispose() {
        }
    }
}

public static void InCallBackFunction(IntPtr hwi, Sound.WimMessageType uMsg, IntPtr dwInstance, IntPtr dwParam1, IntPtr dwParam2)