C# 为什么GetDlgCtrlID总是返回零值？

    private static extern int GetDlgCtrlID(IntPtr hwndCtl);

            private IntPtr rtn_intPtr()
    {
        int 控件ID = 0x00002EE5;
        int 遍历ID = 0;

        WindowInfo[] a = GetAllDesktopWindows();
        for (int i = 0; i < a.Length; ++i)
        {
            遍历ID = GetDlgCtrlID(a[i].hWnd);
            if (遍历ID == 控件ID)
            {
                return a[i].hWnd;      //根据ID取得手柄
            }
        }
        return IntPtr.Zero;
    }