Get device name form GetRawInputDeviceInfo

hi
i want to get device name of HID device using GetRawInputDeviceInfo method of User32.dll. And i am getting window handle from lparam of WndProc Message as mentioned in GetRawInputDeviceInfo function (Windows)[^] but it give pcbSize=0 always.

protected override void WndProc(ref Message m)
        {

            if (m.Msg == 0xFF)
            {
                string deviceName = GetDeviceName(m.LParam);
            }
         }

public string GetDeviceName(IntPtr DeviceHandle)
{
   uint pcbSize = 0;
   string deviceName="";
   GetRawInputDeviceInfo(DeviceHandle, RIDI_DEVICENAME, IntPtr.Zero, ref pcbSize);
   if (pcbSize > 0)
      {
        IntPtr pData = Marshal.AllocHGlobal((int)pcbSize);
        GetRawInputDeviceInfo(DeviceHandle, RIDI_DEVICENAME, pData, ref pcbSize);
        deviceName = Marshal.PtrToStringAnsi(pData);
        Marshal.FreeHGlobal(pData);
        }
   return deviceName;
}

What i am doing wrong here ?
I want to get device name from WndProc message simply.

Tags: C#, Unmanaged