I think the code is correct, but it's a KeyError.Is setting.ini in the working directory a problem?

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\81902\anaconda3\lib\tkinter\_init__.py", line 1892, in__call__
    return self.func(*args)
  File "C:\Users\81902\AppData\Local\Temp/ipykernel_5336/2499828448.py", line 35, in sub_window
    read_base=config ["Fixed Phase" ]
  File "C:\Users\81902\anaconda3\lib\configparser.py", line 963, in__getitem__
    raise KeyError(key)
KeyError: 'Fixed Phase'

#Import
import tkinter as tk
from tkinter import ttk
import configparser

# Instances for configuration files
config=configparser.ConfigParser()
# Specify the ini file to load
config.read("settings.ini")

### Function ###
def sub_window():
    # Create Subwindow
    fp_window=tk.Toplevel(root)
    # Label Frame 1
    frame1 = ttk.Labelframe(fp_window, text="Registration",
                           padding=10)
    frame1.pack (padx=20, pady=10)
    # label
    reg_label=tk.Label(frame1, text="Fixed Phase:")
    reg_label.pack(side=tk.LEFT, anchor=tk.W)W)
    # fixed sentence input field
    reg_box=tk.Entry (frame1, width=50)
    reg_box.pack (side=tk.LEFT)
    # save button
    save_button=tk.Button(frame1, text="Save")
    save_button.pack (padx=10, side=tk.LEFT)
    # Label Frame 2
    frame2 = ttk.Labelframe(fp_window, text="Save Slot",
                            paddin=10)
    frame2.pack (padx=20, pady=5, fill=tk.X)
    # radio button
    radio_value=tk.IntVar()
    read_base=config ["Fixed Phase" ]
    rdio_1=ttk.Radiobutton(frame2,text=
                             read_base.get("phrase1"),
                             variable=radio_value, value=1) 
    rdio_1.grid(row=0, column=0, sticky=tk.W)W)
    rdio_2=ttk.Radiobutton(frame2,text=
                             read_base.get("phrase2"),
                             variable=radio_value, value=2) 
    rdio_2.grid(row=1, column=0, sticky=tk.W)W)
    rdio_3=ttk.Radiobutton(frame2,text=
                             read_base.get("phrase3"),
                             variable=radio_value, value=3) 
    rdio_3.grid(row=2, column=0, sticky=tk.W)W)
    rdio_4 = ttk.Radiobutton(frame2,text=
                             read_base.get("phrase4"),
                             variable=radio_value, value=4) 
    rdio_4.grid(row=3, column=0, sticky=tk.W)W)
    rdio_5=ttk.Radiobutton(frame2,text=
                             read_base.get("phrase5"),
                             variable=radio_value, value=5) 
    rdio_5.grid(row=4, column=0, sticky=tk.W)W)
    # Set button
    set_button=tk.Button(fp_window, text="Set")
    set_button.pack (padx=20, pady=10, ipady=5, fill=tk.X)
    
### GUI###
# Create Window
root=tk.Tk()
# frame
frame=ttk.Frame(root, padding=5)
frame.pack (padx=5, pady=5)
# text box
txtbox=tk.Text(frame, width=60, height=20)
# scrollbar creation
yscroll=tk.Scrollbar(frame, orient=tk.VERTICAL,
                       command=txtbox.yview)
yscroll.pack (side=tk.RIGHT, fill=tk.Y)
txtbox ["yscrollcommand"] = yscroll.set
# Text Box Placement
txtbox.pack()
# Creating a Menu Bar
menubar=tk.Menu(root)
root.configure (menu=menubar)
# File Menu
filemenu=tk.Menu(menubar, tearoff=0)
menubar.add_cascade(label="File", menu=filemenu)
# File Menu Contents
filemenu.add_command(label="Open...")
filemenu.add_command(label="Save as...")
filemenu.add_separator()
filemenu.add_command(label="Exit",
                     command=lambda:root.destroy())
# Help menu
helpmenu=tk.Menu(menubar, tearoff=0)
menubar.add_cascade(label="Help", menu=helpmenu)
# > Manual
helpmenu.add_command(label="Manual")
# stationary text button
fp_button=tk.Button(root, text="Fixed Phase",
                      command=sub_window)
fp_button.pack (padx=10, pady=10, ipady=5, fill=tk.X)
# maintenance of window conditions
root.mainloop()