Zero cross detector isn't working

Projects General Guidance
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hello , i am working on an AC dimmer project , the zero cross detector is workin and delivering a square signal but the arduino doesnt read it . i used a code to count the change in the interrupt pin but it kept showing a zero . here is the code i used :

#define triacpulse 8
int dimming = 128;
volatile int count = 0;
void setup() {
  // put your setup code here, to run once:
    Serial.begin(9600);
pinMode(A0,INPUT);
pinMode(triacpulse, OUTPUT);
  pinMode(2, INPUT_PULLUP);
  
}
void incrementCount() {
  count++; // Increment the count whenever there is a change on pin 2
}
void loop() {
int  sensorValue=analogRead(A0);
  dimming=75*sensorValue;
  attachInterrupt(digitalPinToInterrupt(2),acon,CHANGE);
  attachInterrupt(digitalPinToInterrupt(2), incrementCount, CHANGE);
  Serial.println(count);
  delay(1000); 
}
void acon(){

delayMicroseconds(dimming);
digitalWrite(triacpulse,HIGH);
delayMicroseconds(10);
digitalWrite(triacpulse,LOW);

  
}

the thing i need help with right now is how to read the signal from the zero cross because without it the triac pulse wont come .
any help would be great.
best regards,