winfrom关于播放声音，异常提示 "无法加载 DLL“winmm.dll”

我是vs.net 2005 
用这个播放声音，可是总显示:
"无法加载 DLL“winmm.dll”: 找不到指定的程序。 (异常来自 HRESULT:0x8007007F)。"using System;
using System.Text;
using System.Runtime.InteropServices;namespace FontGame
{
    /**/
    /// <summary>
    /// 
    /// </summary>
    public class sound
    {
        [DllImport("winmm.dll")]
        private static extern int mciSendString
            (
                string lpstrCommand,
                string lpstrReturnString,
                int uReturnLength,
                int hwndCallback
            );        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern int GetShortPathName
            (
                [MarshalAs(UnmanagedType.LPTStr)]    string path,
                 [MarshalAs(UnmanagedType.LPTStr)]    StringBuilder shortPath,
                 int shortPathLength
            );        public sound()
        {        }        public void Play(string FileName)
        {
            StringBuilder shortPathTemp = new StringBuilder(255);
            int result = GetShortPathName(FileName, shortPathTemp, shortPathTemp.Capacity);
            string ShortPath = shortPathTemp.ToString();            mciSendString("open " + ShortPath + " alias song", "", 0, 0);
            mciSendString("play song", "", 0, 0);
        }        public void Stop()
        {
            mciSendString("stop song", "", 0, 0);
        }        public void Pause()
        {
            mciSendString("pause song", "", 0, 0);
        }        public void Close()
        {
            mciSendString("close song", "", 0, 0);
        }
    }
}哪位大虾是知道怎么回事，感激不尽。