Camera Control

Ok, great, I have removed the stick and boiled my code down to what is below but still no joy, I'm suspecting there is a problem with my hardware, specifically the max485, I have a 100ohm resistor across pins 6+7 as well as an led to show data output. When I remove the camera from the output of the max485, the led blinks when it should, reconnect the camera wires, no blinking.

byte CurrCameraAddress = 0x01;
byte SynchByte = 0x00;
byte PanSpeed = 0x10;
byte TiltSpeed = 0x10;

int MAX485 = 3;

byte command1 = 0x00;
byte command2 = 0x02;  //should go right

void setup()
{
  Serial3.begin(2400);         //  setup serial for commands
  pinMode(MAX485, OUTPUT);
}

void loop()
{
  digitalWrite(MAX485, HIGH);
  delay(1);
  Serial3.flush();
  
  byte checkSum = ((byte)CurrCameraAddress + (byte)command1 + (byte)command2 + (byte)PanSpeed + (byte)TiltSpeed)%256;
  Serial3.write((byte)SynchByte); // Synch Byte
  Serial3.write((byte)CurrCameraAddress); //Camera Address
  Serial3.write((byte)command1);  
  Serial3.write((byte)command2);
  Serial3.write((byte)PanSpeed); //Pan Speed
  Serial3.write((byte)TiltSpeed); //Tilt Speed
  Serial3.write((byte)checkSum); //check sum is the sum of bytes (excluding the synchronization byte) modulo 256
   
  //set the MAX485 to STOP send data
  digitalWrite(MAX485, LOW);
}