arduino code nedded Answered

HI, MY  NAME IS THIAGO IKEDA AND HERE IS MY FIRST "ASK"

my english is VERY bad. well sorry anyway

FIRST  i made this arduino tank (named ardutank) with ladyada motor shield
and i used library and worked
then i like WOW I SUPER GENIUS

so i buy an HC-SR04(ULTRASONIC SENSOR) to put with ARDUTANK, and i used the library too
but when i upload the code the ARDUTANK START make some wild noises.
i dont know what to do to ARDUTANK work with the sensor


obs: in first mode (with out ultrasonic sensor) one motor spins more fast than other, WHY?
the bouth motors are the same motor. but when i put to HIM to RUN HE make lil curve.

here is code WITH SENSOR


PLEASE IGNORE THE RELE AND BUZER NEXT TO SENSOR



// Adafruit Motor shield library
// copyright Adafruit Industries LLC, 2009
// this code is public domain, enjoy!

#include
#include

#define TRIGGER_PIN  12
#define ECHO_PIN     13
int distance;
Ultrasonic ultrasonic(TRIGGER_PIN, ECHO_PIN);

AF_DCMotor motor1(1);
AF_DCMotor motor2(2);


void setup() {
  Serial.begin(9600);           // set up Serial library at 9600 bps
  Serial.println("Motor test!");

  // turn on motor

  delay(10);
  motor1.setSpeed(20);
  motor2.setSpeed(20);
motor2.run(RELEASE);
  motor1.run(RELEASE);
}

void loop() {
  uint8_t i;
  float cmMsec, inMsec;
  long microsec = ultrasonic.timing();

  cmMsec = ultrasonic.convert(microsec, Ultrasonic::CM);
  inMsec = ultrasonic.convert(microsec, Ultrasonic::IN);


  Serial.print("tick");

  motor1.run(FORWARD);
  motor2.run(FORWARD);
  if(distance<10)
{
   motor1.run(RELEASE);
   motor2.run(RELEASE);
}
else
{
   motor1.run(FORWARD);
  motor2.run(FORWARD);
}

}