I thought I had the Millis() command sorted but i'm stumped on the one. Aim is to get 2 led's alternately dimming, they work great with delay(); of course....but i can't figure where i'm going wrong with Millis().
Please have a look and point out what i've got wrong.
Thanks
Doug




int LED3 = 5;
int LED4 = 6;

// each "event" (LED) gets their own tracking variable
unsigned long previousMillisLED3=0;
unsigned long previousMillisLED4=0; 

int intervalLED3 = 500;
int intervalLED4 = 500;

void setup() {
    pinMode(LED3, OUTPUT);
    pinMode(LED4, OUTPUT);

      digitalWrite(LED3,LOW);
      digitalWrite(LED4,LOW);

}

void loop() {
  //unsigned long currentMillis = millis();
      for(int P=0;P<6;P++){
        //if ((unsigned long)(currentMillis - previousMillisLED3) >= intervalLED3) {
            analogWrite(LED3, 127);
            analogWrite(LED4, 254);             
        delay(500);
              //previousMillisLED3 = currentMillis;
    
      //if ((unsigned long)(currentMillis - previousMillisLED4) >= intervalLED4) {
            analogWrite(LED3, 254);
            analogWrite(LED4, 127);
       delay(500); 
             //previousMillisLED4 = currentMillis;
      }    
}


Sorry, problems inputting code, but its all there.  
I realize that there are some closing brackets missing in the LOOP() section for millis but it is set for delay() to show that it works.