Java The method is undefined for this type

I am having a problem with calling a method that is in a different class. This main method is in a class on its own called lab14, and the heapSort() method is in a different class called HeapSort. Both of these classes are in the default package. I am getting the error “The method heapSort(Vector) is undefined for the type Lab14” and I don’t understand why, please help.

below is the main method in the lab 14 class

public static void main(String args[]) {

    Heap myheap = new Heap();
    Vector<StudentGPA> vec = new Vector();
    int []  br = new int[20]; 
    double []  dr = new double[20]; 
    int i = 0;
    int j = 0;
    try {
    //String inputLine; //stores each line from the file
    Scanner scanLine;
    Scanner input = new Scanner(new File(""));
    while (input.hasNextLine()){
    scanLine = new Scanner(input.nextLine());

    int id = scanLine.nextInt();
    //br[i] = id;
    String name =;
    double gpa = scanLine.nextDouble();
    //dr[i]= gpa;
         String advisor =;
         GraduateStudentGPA grad = new GraduateStudentGPA(id,name,gpa,advisor);
        StudentGPA reg = new StudentGPA(id,name,gpa);
catch (IOException e) {
    System.out.println("IOException in reading input file!!!"+e);

Below is the code for the HeapSort class

public class HeapSort <E extends Comparable<? super E>>{
/** sorts the input vector using heap Sort <ul> <li> iterates
 * through each element of the input vector and inserts each
 * element to the heap by calling {\tt heapInsert}.  <li> deletes
 * each of the inserted items by calling {\tt heapDelete} the
 * appropriate number of times, and fills up the vector with the
 * returned elements.  </ul> If you are using the
 * minheap implementation, this insertion and deletion of all
 * items will produce a list of items sorted by their key
 * attribute values.
 * @param vec input vector
public void heapSort(Vector<StudentGPA> vec){
    //  --  TO COMPLETE  --
    Heap myheap = new Heap<E>();
    for(int i = 0; i <vec.size(); i++)
    for(int i = 0; i <vec.size(); i++)
        vec.setElementAt((StudentGPA) myheap.heapDelete(), i);



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