Incompatible types error

//This is my Example.java file
public class Example {

    public static void main(String[] args) {
        // Your amazing code goes here...
        System.out.println("We are a making a new Pez Dispenser.");
        PezDispenser dispenser = new PezDispenser("Bob.");
        System.out.printf("The dispenser character is %s\n",
                          dispenser.getCharacterName());
      if (dispenser.isEmpty()){
        System.out.println("It is currently empty");
      }
      System.out.println("Loading...");
      dispenser.load();
      if (!dispenser.isEmpty()){
      System.out.println("Still have some pez!");
      }
    }
}
//This is my PezDispenser file
public class PezDispenser {
  public static final int MAX_PEZ = 12;
  private String mCharacterName;
  private int mPezCount;

  public PezDispenser(String characterName){
    mCharacterName = characterName;
    mPezCount = 0;
  }
    public boolean isEmpty(){
  return mPezCount = 0;

    }

  public void load(){
    mPezCount = MAX_PEZ;
  }

  public String getCharacterName() {
    return mCharacterName;
  }
}