OS: windows ce6.0

code:

private void btnFind_Click(object sender, EventArgs e)
        {
            try
            {
                BluetoothRadio.PrimaryRadio.Mode = RadioMode.Discoverable;
                bluetoothClient = new BluetoothClient();
                InTheHand.Net.Sockets.BluetoothDeviceInfo[ bluetoothDeviceInfo = (new BluetoothClient()).DiscoverDevices(10, false, false, true);
                //Guid spguid = InTheHand.Net.Bluetooth.BluetoothService.ObexObjectPush;
                cmbBlueTooth.DataSource = bluetoothDeviceInfo;
                cmbBlueTooth.DisplayMember = "DeviceName";
                cmbBlueTooth.ValueMember = "DeviceAddress";
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
            }
        } 

Error:Can't find PInvoke DLL 'BthUtil.dll'

Why??

I'm not the WM/WinCE guy, but from an earlier answer of Peter's http://inthehand.com/forums/t/1178.aspx its the case that not all CE vendors ship that DLL.  Maybe they just missed it and they could do so...

It looks like the bthutil.dll is not supported under CE. 
 
It is in PPC and Smartphone API.  

 It  might be possible to create your own version of BthUtil.  To make the device 
 
discoverable on CE look at BthWriteScanEnableMask().  You want to use 
 
mask=0x2 for "On" and mask=0x3 for "discoverable". 

Since Windows Mobile supports the BthReadScanEnableMask and BthWriteScanEnableMask (the BthUtil functions are obviously simple wrappers around these) I'll be replacing the code for the next release so that it removes this dependency.

Peter