TreeView column headers

[TWB]

Hello all
I have posted a code section of a larger program where im trying to populate a a treeview with 2 columns and inset 2 values.
My issue is the treeview will show but the 2 column headers will not display as well as the 2 values.
thank you for any direction

# Introduction to Python Programming
from tkinter import *
import shelve
from tkinter import ttk
class MyFrame (Frame):
    def __init__(self):
        Frame.__init__(self)
        self.master.geometry("600x600")
        self.master.title("Student Scores")
        self.grid()
           
        #Create and define a TreeView
        columns = ("student", "score")
        self.treeview = ttk.Treeview(self, columns = columns, show = "headings")
        self.treeview.column("student",anchor=CENTER, stretch=NO, width=20)
        self.treeview.heading("student", text="Student")
        self.treeview.column("score",anchor=CENTER, stretch=NO, width=20)
        self.treeview.heading("score", text="Score")
        self.treeview = ttk.Treeview(self, height = 15)
        self.treeview.grid(padx = 50, pady = 50)
        #insert values to column
        self.treeview.insert('', 'end', text="Student", values=('Jon', '99'))
        
asn_frame = MyFrame()
asn_frame.mainloop()