Even though I called assist method I get error message: "Did you remember to call the assist method on the Customer...

import java.util.ArrayDeque;
import java.util.Queue;

public class CallCenter {
    Queue<CustomerSupportRep> mSupportReps;

    public CallCenter(Queue<CustomerSupportRep> queue) {
        mSupportReps = queue;
    }

    public void acceptCustomer(Customer customer) {
        CustomerSupportRep csr;

        while (mSupportReps.poll() == null) {
            playHoldMusic();
        }
        /********************************************
         * TODO (1)
         * Wait until there is an available rep in the queue.
         * While there is not one available, playHoldMusic
         * HINT: That while assignmentcheck loop syntax we used to
         *      read files seems pretty similar
         ********************************************
         */

        csr = new CustomerSupportRep("Dre");
        csr.assist(customer);


        /********************************************
         * TODO (2)
         * After we have assigned the rep, call the
         * assist method and pass in the customer
         ********************************************
         */

        mSupportReps.add(csr);

        /********************************************
         * TODO (3)
         * Since the customer support rep is done with
         * assisting, put them back into the queue.
         ********************************************
         */

    }

    public void playHoldMusic() {
        System.out.println("Smooooooth Operator.....");
    }

}

import java.util.List;
import java.util.ArrayList;

public class CustomerSupportRep {
  private String mName;
  private List<Customer> mAssistedCustomers;

  public CustomerSupportRep(String name) {
    mName = name;
    mAssistedCustomers = new ArrayList<Customer>();
  }

  public void assist(Customer customer) {
    System.out.printf("Hello %s, my name is %s, how can I assist you.%n",
                      customer.getName(),
                      mName);
    System.out.println("...");
    System.out.println("Is there anything else I can help you with?");
    mAssistedCustomers.add(customer);
  }

  public List<Customer> getAssistedCustomers() {
    return mAssistedCustomers;
  }

}

public class Customer {
  private String mName;

  public Customer(String name) {
    mName = name;
  }

  public String getName() {
    return mName;
  }

}