Arduino pins not working I'm building my first arduino project and I encountered a strange problems;

I build a haunted house based upon that instructables tutorial:
https://www.instructables.com/id/Control-Your-Halloween-Decorations-With-Arduino/

Every prop works, I tried to light them on and off (it works), but when I try to use all of them, a few doesn't work.

There is my code; Is it something I'm doing wrong?

int propSqueDans = 4; 
int propClownImmo = 5;
int propClownJambes = 6;
int propSqueBal = 7;
int propSqueMini = 8;
int propSpider = 9; 
int propChauSou = 10;
int propFantChai = 11; 

int SensorPin = 3; // sensor connected to analog pin 3 
int SensorVal = 0; // variable to store the value read

void setup() { 
  pinMode(propSqueDans, OUTPUT);// sets the digital pin as output 
  pinMode(propClownImmo, OUTPUT);
  pinMode(propClownJambes, OUTPUT);
  pinMode(propSqueBal, OUTPUT);
  pinMode(propSqueMini, OUTPUT);
  pinMode(propChauSou, OUTPUT);
  pinMode(propFantChai, OUTPUT);
  pinMode(propSpider, OUTPUT);
  Serial.begin(9600);

  }

void loop() { 
    SensorVal = analogRead(SensorPin); // read the input pin

    if (SensorVal &gt;100) {
    Serial.write("Danse + Clown Immo \n"); 
    digitalWrite(propSqueDans, HIGH); 
    digitalWrite(propClownImmo, HIGH); 
    delay(10000); 
    Serial.write("Spider + Fangtôme + Clown jambes \n"); 
    digitalWrite(propSpider, HIGH); 
    digitalWrite(propFantChai, HIGH);
    digitalWrite(propClownJambes, HIGH); 

    delay(5000);
    Serial.write("Squelette balance + sque mini \n");
    digitalWrite(propSqueBal, HIGH); 
    digitalWrite(propSqueMini, HIGH); 

    delay(5000);
    Serial.write("Chauve souris \n");
    digitalWrite(propChauSou, HIGH);

    delay(20000);


    digitalWrite(propSqueDans, LOW); 
    digitalWrite(propClownJambes, LOW); 
    digitalWrite(propSqueBal, LOW); 
    digitalWrite(propSqueMini, LOW); 
    digitalWrite(propChauSou, LOW); 
    digitalWrite(propFantChai, LOW); 
    digitalWrite(propSpider, LOW); 
    digitalWrite(propClownImmo, LOW); 
    delay(5000); 
    }

  }


Thank you for your help !
My best guess (not knowing what the pins are driving) is that your trying to draw too much current from the Arduino gpio.

Ref: https://playground.arduino.cc/Main/ArduinoPinCurrentLimitations