Flask: Making my first web site

[Truman]

after adding some stuff to the app...

from flask import Flask, render_template, url_for, flash, redirect
from forms import RegistrationForm, LoginForm 

app = Flask(__name__)

app.config['SECRET_KEY'] = '24b6f628700853713c55abab2a9d8309'

posts = [
    {
	    'author': 'Corey Schafer',
		'title': 'Blog Post 1',
		'content': 'First post content',
		'data_posted': 'April 20, 2018'
	},
	{
	    'author': 'Jane Doe',
		'title': 'Blog Post 2',
		'content': 'Second post content',
		'date_posted': 'April 21, 2018'
	}
]

@app.route("/")
@app.route("/home")
def home():
    return render_template('home.html', posts=posts)
	
@app.route("/about")
def about():
	return render_template('about.html', title='About')

@app.route("/register", methods=['GET', 'POST'])
def register():
	form = RegistrationForm()
	if form.validation_on_submit():
		flash(f'Account created for {form.username.data}!', 'success')
		return redirect(url_for('home'))
	return render_template('register.html', title='Register', form=form)
	
@app.route("/login")
def login():
	form = LoginForm()
	return render_template('login.html', title='Login', form=form)

if __name__ == '__main__':
	app.run(debug=True)

...receive an error

Error:
AttributeError: 'RegistrationForm' object has no attribute 'validation_on_submit'

any idea why is this happening?