When I try to call a method from another class I get an "Error: identifier is undefined"

I have two classes, LinkedList and HashTable, and when I try to call a method from LinkedList, specifically insertListElement(), in the insertElement() method of Class HashTable, it gives a compilation error: "Error: identifier insertListElement is undefined" How do I successfully call this method?

Here is my code:

    // Assignment #4
    // Name: Dylan Rich
    // ASU Email Address: drich2@asu.edu
    // Description: To be completed

    #include "stdafx.h"
    #include <string> //to use strings


    using namespace std;

    int main()
    {
        return 0;
    }

    //class LinkedList will contains a linked list of courses
    class LinkedList
    {
    private:
        LinkedList *next;
    public:
        string courseNum;   //the number code of the course
        string courseTitle; //the title of the course
        LinkedList();       //constructor
        ~LinkedList();      //destructor
        void setStrings(string num, string title);  //sets the data for the node
        bool insertListElement(LinkedList *oldHead, LinkedList *newHead);           //inserts an element at the beginning of the list
        LinkedList *searchListElement(LinkedList *toSearch, LinkedList *head);      //searches for an element and returns it
        bool deleteListElement(LinkedList *head, LinkedList *toDelete);     //deletes an element at the list, returns false if no such element
        void setNext(LinkedList *nextNode); //sets a specific node as next
        LinkedList *getNext();  //retrieves the next node
    };

    //Constructor
    LinkedList::LinkedList()
    {

    }

    //Deconstructor
    LinkedList::~LinkedList()
    {
        delete next;
        next = NULL;
    }

    //sets the data for the node
    void LinkedList::setStrings(string num, string title)
    {
        courseNum = num;
        courseTitle = title;
        next = NULL;
    }

    //inserts an element at the beginning of the list
    bool LinkedList::insertListElement(LinkedList *oldHead, LinkedList *newHead)
    {
        if (oldHead == NULL)    //if list is empty, it's automatically the head     and returns false
            return false;
        newHead->setNext(oldHead);  //otherwise it becomes the new head and     returns true
        return true;
    }

    //searches for an element and returns it
    LinkedList *LinkedList::searchListElement(LinkedList *toSearch, LinkedList     *head)
    {
        LinkedList *temp = NULL;    //creates a temporary node
        if (head == NULL)   //if list is empty return false
            return temp;
        while (head->getNext() != NULL)//while the list still has elements
        {
            if ((head->courseNum.compare(toSearch->courseNum)) == 0 && (head-   >courseTitle.compare(toSearch->courseTitle)))//if this is the one we're looking     for, return it
                return head;
            head = head->getNext(); //move to the next element in the list
        }
        return temp;
    }

    //Delete an element from the list
    bool LinkedList::deleteListElement(LinkedList *head, LinkedList *toDelete)
    {
        LinkedList *temp = NULL;    //creates a temporary node
        if (head == NULL)   //if list is empty return false
            return false;
        do
        {
            //if this is the one we're looking for
            if ((head->courseNum.compare(toDelete->courseNum)) == 0 && (head->courseTitle.compare(toDelete->courseTitle)))
            {
                temp->setNext(head->getNext());
                head->~LinkedList();
                return true;
            }
            temp = head;
            if (head->getNext() != NULL)
                head = head->getNext();
        } while (head->getNext() != NULL);
        return false;
    }

    //Sets a specfic node as next
    void LinkedList::setNext(LinkedList *nextNode)
    {
        next = nextNode;
    }

    //shows which node next is pointing to
    LinkedList * LinkedList::getNext(void)
    {
        return next;
    }
    //End class LinkedList



    //class HashTable contains a hash table of linked lists of courses
    class HashTable
    {
    public:
        LinkedList ** hash; //hash table
        HashTable(int length);  //constructor
        int h(LinkedList *element, int hashSize);   //hash function
        bool insertElement(int key, LinkedList *element);   //inserts an element at a key
        LinkedList *searchElement(LinkedList *element);     //searches for and returns an element
        bool deleteElement(LinkedList *element);            //deletes an element
    };

    //Constructor
    HashTable::HashTable(int length)
    {
        hash = new LinkedList* [length];
    }

    //Hash function, the key is the sum of the numbers making up the course code
    int HashTable::h(LinkedList *element, int hashSize)
    {
        int a, b, c, key;
        a = element->courseNum.at(3);
        b = element->courseNum.at(4);
        c = element->courseNum.at(5);
        key = (a + b + c) % hashSize;
        return key;
    }

    //inserts an element at a specific key, returns true if successful
    bool HashTable::insertElement(int key, LinkedList *element)
    {
        LinkedList *temp = hash[key];
        bool joined = insertListElement(temp, element);
        hash[key] = element;strong text
    }

Most of it is irrelevant except the two methods I mentioned earlier.