Connection of Arduino to Quctel EC200U CN ttl Modem

wanted to connect this device to Arduino. I want to send data from arduino to this module. I have connected the rx pin on arduino to txd pin on the device and txd pin of device to rxd of arduino . I have connected 5v pin of arduino to 5v pin of this device and ground pin of this device to ground pin of Arduino. It is not working. I am a newbie. Can you guys help me ?