Not receive data when software connect with usb device

See more:

C#

I am developing serial port data receive and sending software in C#.My software work fine if i am not connected it with any USB device but when i connect my software with any USB device and send or receive data then i will not work is then any other code for receive USB connected device data.
I use this code for receive data:

void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            try
            {
                if (comPort.IsOpen == true)
                {
                    bytes = comPort.BytesToRead;
                    comBuffer = new byte[bytes];
                    comPort.Read(comBuffer, 0, bytes);
                }
            }
            catch (Exception ex)
            {
            }
        }  

Help me to solve this.

[edit]Code block added, "Treat my content as plain text..." option disabled - OriginalGriff[/edit]