xml to csv conversion:'NoneType' object has no attribute 'text'' - ElementTree

I am trying to learn how to convert xml to csv format and looked up some tutorials. I am doing the following, but getting an error: 'NoneType' object has no attribute 'text''

So the part XML file is the following (it is actually bigger, but I reduced it for the sake of example):

<?xml version="1.0" encoding="UTF-8" standalone="true"?>

-<ns2:export xmlns:ns2="http://zakupki.gov.ru/oos/export/1" xmlns="http://zakupki.gov.ru/oos/types/1">

-<ns2:fcsNotificationZK schemeVersion="1.0">

<id>27778</id>

<purchaseNumber>0373100113714000006</purchaseNumber>

<docPublishDate>2014-01-24T18:40:51.599+04:00</docPublishDate>

And then I am writing the following code to get the tag and the information for the tag:

import csv
import xml.etree.cElementTree as ET

tree = ET.parse("xml_notification_example.xml")
root = tree.getroot()

xml_data_to_csv = open('out.csv', 'w')
list_head = []
csv_writer = csv.writer(xml_data_to_csv)

count = 0

for element in root:
    list_nodes = []
    
    if count == 0:
        root.findall('id')
        list_head.append('id')

        root.findall('purchaseNumber')
        list_head.append('purchaseNumber')

        root.findall('docPublishDate')
        list_head.append('docPublishDate')
        
        csv_writer.writerow(list_head)
        count = +1
    
    iden = element.find('id').text
    list_nodes.append(iden)
    
    purchaseNumber = element.find('purchaseNumber').text
    list_nodes.append(purchaseNumber)
       
    docPublishDate = element.find('docPublishDate').text
    list_nodes.append(docPublishDate)
    
    csv_writer.writerow(list_nodes)

xml_data_to_csv.close()

And I get the mistake:

---> 19     iden = element.find('id').text
     20     list_nodes.append(iden)
     21 

AttributeError: 'NoneType' object has no attribute 'text'

Can you,please, give me a clue what is wrong here, even intuitively?