4 Relay Module but only 2 working

Just received an 5V 4 Channel Relay Module 10A (CE05279) but can only get relay 3 & 4 to work. Trying to isolate the problem by the following.

  • Connected Arduino +5 to relay board VCC
  • Connected Arduino GND to Relay Board GND
  • Connected Arduino PIN 6 to each relay board In Pin (1-4) in turn running the following simple sketch

#define RELAYPIN 6

void setup()
// Initialise the Arduino data pins for OUTPUT


void loop()
digitalWrite(RELAYPIN,LOW); // Turns ON Relays 2
delay(2000); // Wait 2 seconds
delay(2000);// Turns Relay Off

For Relay board IN 3 & 4 works as expected (LED goes on and you can hear the relay click). For IN 1 & 2 there is no LED and no Relay click. Apart from the relay board being DOA any other thoughts?