I can't make the pid_speed work..

hi stanley
i wrote this code but i doesn't work… and its only blink the led… after i want to print the speed in kph in some java program… i will very grateful if you can help me.. thanks
(the rpm pid works fine).


#include <Arduino.h>
#include <OBD.h>
#include <Wire.h>

COBD obd;

void setup()
{
pinMode(13, OUTPUT);
pinMode(A0, OUTPUT);
pinMode(A1, OUTPUT);

obd.begin();

while (!obd.init());
}

void loop()
{
int value;
int vel;

if (obd.read(PID_SPEED, kph)){
digitalWrite(13, vel = 0 ? HIGH : LOW);
digitalWrite(A0, vel >= 100 ? HIGH : LOW);
}
if (obd.read(PID_RPM, value)) {
digitalWrite(A1, value > 900 ? HIGH : LOW);
}
}