Cannot transmit and receive at the same time using Uno, HC-05 & Adroid phone

I am connecting my Arduino Uno to HC-06 bluetooth module (FC-114), I had a strange problem that I had not figured out its solution yet...

I cannot transmit and receive data at the same time from the Bluetooth terminal at my Android phone.

However, when I disconnect the Arduino Rx, I can transmit from the Arduino and I receive it successfully at my Android phone terminal.

And, when I disconnect the Arduino Tx, I can receive at the Arduino what ever I send from my Android phone terminal.

I use this test code,

int incomingByte = 0;   // for incoming serial data
int ledpin=13; // led on D13 will show blink on / off

void setup() {
        Serial.begin(9600);     // opens serial port, sets data rate to 9600 bps
        pinMode(ledpin,OUTPUT);
        digitalWrite(ledpin,0);
}

void loop() {

        // send data only when you receive data:
        if (Serial.available() > 0) {
                // read the incoming byte:
                incomingByte = Serial.read();

                if (incomingByte == '1'){
                digitalWrite(ledpin,1);
                // say what you got:
                Serial.print("I received: ");
                Serial.println(incomingByte, DEC);
                }
                if (incomingByte == '0'){
                digitalWrite(ledpin,0);
                // say what you got:
                Serial.print("I received: ");
                Serial.println(incomingByte, DEC);
                }
                }
        }

Is your serial monitor disconnected while all this is going on?

Yes, it is.

I have used it to guarantee that the arduino is functioning well and it was,then I had disconnected the serial monitor.

I guess that the malfunction is at the HC-05 side.

Not very likely but check closely round the pins for solder bridges. It is the only fault situation I am aware of and maybe you are fixing it by removing the connector.

Here are some basic notes.

http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino