Binary Search Tree Help!

Im trying to insert items into a BST from a txt file.

For arguments sake the data file is just the integers 1 2 3 4 5 6 7 8 9.

When i try to do a inorder traversal, all that is outputting is the first and last number.

I think the problem is with the creating the BST though i'm not sure what it is?

#include <cstdlib>
#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

struct BST
{
    int data;
    BST *left;
    BST *right;
};

void menu(); //Displays menu options.

void buildBST(BST *& tree);

void printInorder(BST * p);

BST * tree = new BST;

int main()
{
    cout << " Binary Search Tree Balancing and Drawing" << endl;

    menu();
   
    system("PAUSE");
    return EXIT_SUCCESS;
}

void menu()
{
    int choice;

    cout << "\tMenu" << endl;
    cout << " 1.  Build new binary search tree" << endl;
    cout << " 2.  Display inorder traversal" << endl;
    cout << " 3.  Save tree (as preorder traversal)" << endl;
    cout << " 4.  Balance tree" << endl;
    cout << " 5.  Draw tree" << endl;
    cout << " 6.  Quit" << endl;
    
    cout << " Choice ? ";
    cin >> choice;
    
    switch (choice)
    {
         case 1:
              buildBST(tree);                    
              break;
         case 2:
              printInorder(tree);
              break;
         case 3:
              break;
         case 4:
              break;
         case 5:
              
              break;
         case 6:
              
              break;
    }
}

void buildBST(BST *& tree)
{     
    int array [100];
    int index = 0;
    int output;
    int number;   //To store a[i] in.
    tree = NULL;  //To ensure the tree is built fresh.
    
    ifstream infile;
    string fileName;
    
    cout << "Please enter name of data file" << endl;
         cin >> fileName;
    
    infile.open(fileName.c_str());
    
    if (!infile)
    {
         cout << "Cannot find " << fileName << endl;
         cout << endl;
         menu();
    }  
    
    if (infile.is_open()) 
    {
         while (!infile.eof()) 
         {
              infile >> output;
              array[index];
              index++;
              
              BST * t = new BST;
              t -> data = output;
              t -> left = NULL;
              t -> right = NULL;
              
              if (tree == NULL) 
              {
                   tree = t;
                   cout << "NULL = " << t -> data << endl;
              }
              
              else if (output < tree -> data) 
              {
                   tree -> left = t;                   
                   cout << "LEFT = " << t -> data << endl;                   
              }
              
              else // (output > tree -> data)
              {
                   tree -> right = t;                  
                   cout << "RIGHT = " << t -> data << endl;   
              }     
         }
    } 
    
    cout << endl;
    menu();
}

void printInorder(BST * tree)
{
    if (tree != NULL) 
    {
        printInorder (tree -> left);  // print left subtree
        cout << tree -> data << endl; // print this node
        printInorder (tree -> right); // print right subtree
    }
}