Cant get the SRF02 to work in seriell mode

HI!

I have an srf02 attached to a Mega 2560 in seriell mode. i can see that the sensors led is flashing but i cant get the correct values from it. the output is

Range: 0 Range: 171 Range: 0 Range: 171 Range: 0 Range: 171 Range: 0 Range: 171 Range: 0 Range: 171 Range: 0 Range: 171

then after a while i just get 0

here is my code

//SRF02

define srfAdrs 00 // Address of the SRF02

define rangeCM 84 // Byte for start of ranging data

void setup() { Serial1.begin(9600); Serial.begin(9600); }

void loop() { SRF_Range(); }

void SRF_Range(){

int incomingByte=0;

Serial1.write(byte(00)); // send address byte delay(100); Serial1.write(byte(84)); //send command byte delay(70);

if (Serial1.available() > 0) { //Serial.write(byte(94)); incomingByte = Serial1.read(); // read serial response Serial.print("Range: "); Serial.println(incomingByte); // write distance measured Serial1.flush(); // clear buffer delay(100); } }

what is wrong?