Using IR Proximity Sensor to control motors

Hi all, I'm struggling to use the output of my IR sensors(2 sensors) to control 2 motors.
I am using 2 Sharp IR GP2Y0D340K Distance sensor , a Ardumoto to power the motors and a Arduino Uno. When I connect power to the Arduino the motors turn as expected , but only keep turning in one direction. I want the motors to change direction when the IR sensor detects an object, but they do not respond to the sensors. In my code I have assigned the sensors readings( 1 or 0 ) to be sent to the serial monitor just so that I can see if they are working, and they are. Can someone please take a look at my code and why the motors do not respond. Thanks in advance.

int pwm_a = 3;  //PWM control for motor outputs 1 and 2 is on digital pin 3
int pwm_b = 11;  //PWM control for motor outputs 3 and 4 is on digital pin 11
int dir_a = 12;  //dir control for motor outputs 1 and 2 is on digital pin 12
int dir_b = 13;  //dir control for motor outputs 3 and 4 is on digital pin 13


void setup()
{
  pinMode(pwm_a, OUTPUT);  //Set control pins to be outputs
  pinMode(pwm_b, OUTPUT);
  pinMode(dir_a, OUTPUT);
  pinMode(dir_b, OUTPUT);
  
  Serial.begin(9600); 
   
   analogWrite(pwm_b, 220);
   analogWrite(pwm_a, 220);        
}

void loop()
{
   int sensorValue = digitalRead(A0);
   int sensorValue1 = digitalRead(A1);
   Serial.println(sensorValue1, DEC);//Just to see if the sensors are working, and they are
   
  if (sensorValue = 0) {            //Sensor 1 is asigned to only control the left-side motor
   void LFORWARD(); 
 }
    else{
   void LREVERSE();
    }    

  if(sensorValue1 = 0){           //Sensor 2 is asigned to only control the right-side motor
   void RFORWARD(); 
   }
    else{
   void RREVERSE();
   } 
void LFORWARD();{
  digitalWrite(dir_a,HIGH);//Control for the left-side motor
}
void RFORWARD();{
  digitalWrite(dir_b,HIGH);//Control for the right-side motor
}
void LREVERSE();{
   digitalWrite(dir_a,LOW);//Control for the left-side motor
}
void RREVERSE();{
  digitalWrite(dir_b,LOW);//Control for the right-side motor
}
}

This:

  if (sensorValue = 0)

Should be this:

  if (sensorValue == 0)

Thanks wildbill but the change didn't work. In the place of the motors I plased an LED to check if they would work, and they did work but the light emitted by them was really dim.

void LFORWARD();{

Lose the semicolons.

Thanks AWOL but by removing the semicolons it doesn't want to compile, sorry, what do you think is wrong?

what do you think is wrong?

I think that this version of C doesn't like nested function declarations.
Move the functions out of loop, and LOSE THE SEMICOLONS.