Multiple constructors ? (exercise from Deitel's C++ Book)

Hi,

I'm a novice working through the Deitel, C++ How to Program book.

I just finished reviewing the chapter on classes and I'm stuck on the following exercise:

 (Modifying Class GradeBook) Modify class GradeBook (Fig. 3.11–Fig. 3.12) as follows:
 a) Include a second string data member that represents the course instructor’s name.
 b) Provide a set function to change the instructor’s name and a get function to retrieve it.
 c) Modify the constructor to specify two parameters—one for the course name and one for the instructor’s name.
 d) Modify member function displayMessage such that it first outputs the welcome message and course name, then outputs “This course is presented by:” followed by the instructor’s name.
 Use your modified class in a test program that demonstrates the class’s new capabilities.
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I had success in (a) (b) but (c) is not working as expected.  I think its a syntax error in the constructor, any how here is the code I have:

gradebook.h

#include <string>
using std::string;

// GradeBook class definition
class GradeBook
{
public:
      GradeBook( string ); // constructor that initializes courseName
      void setCourseName( string ); // function that sets the course name
      string getCourseName(); // function that gets the course name
      void displayMessage(); // function that displays a welcome message

      void setInstructorName( string );
      string getInstructorName();

private:
      string courseName; // course name for this gradebook
      string instructorName;
};


gradebook.cpp

#include <iostream>
using std::cout;
using std::endl;

#include "gradebook.h"

// constructor initializes courseName with string supplied as argument
GradeBook::GradeBook( string name )
{
      setCourseName( name );
      setInstructorName (name );

}

// function to set the course name
void GradeBook::setCourseName( string name )
{
      if (name.length() <= 5)
            courseName = name;

      if (name.length() > 5)
      {
            courseName = name.substr(0, 5);

            cout << "Name \ " << name << "\ exceeds maximum length (5).\n"
             << "Limiting courseName to first 5 characters.\n" << endl;
      } //end if statement
}

// function to get the course name
string GradeBook::getCourseName()
{
      return courseName;
}

//display a welcome message to the gradebook user
void GradeBook::displayMessage()
{
      // call getCourseName to get the courseName
      cout << "Welcome to the grade book for\n" << getCourseName()
            << "!" << endl;
}

void GradeBook::setInstructorName( string name )
{
      instructorName = name;
}

string GradeBook::getInstructorName()
{
      return instructorName;
}

lesson03.cpp

#include <iostream>
using std::cout;
using std::endl;

#include "GradeBook.h"

int main()
{
      GradeBook gradebook1( "12345" );
      GradeBook gradebook2( "654321" "bob" );


      cout << "gradebook1 created for course: " << gradebook1.getCourseName()
            << "\ngradebook2 created for course: " << gradebook2.getCourseName()
            << " and the instructor is called " << gradebook2.getInstructorName()
            << endl;

      return 0;
}

Thanks for any guidance.