问Python ValueError: XPath错误:未注册的函数

EN

<img alt="MediaMarkt" border="0" e-editable="img" src="http://news-de.mediamarkt.de/custloads/298149669/vce/mediamarkt.png" style="display:block;" width="169"/>

company_name = "mediamarkt"
response.xpath(f'//img[lower-case(@alt)="{company_name.lower()}"]') #Error
response.xpath(f"//img[matches(@alt,'{company_name}','i')]") # Error

Traceback (most recent call last):
  File "/home/timmy/.local/lib/python3.8/site-packages/parsel/selector.py", line 254, in xpath
    result = xpathev(query, namespaces=nsp,
  File "src/lxml/etree.pyx", line 1582, in lxml.etree._Element.xpath
  File "src/lxml/xpath.pxi", line 305, in lxml.etree.XPathElementEvaluator.__call__
  File "src/lxml/xpath.pxi", line 225, in lxml.etree._XPathEvaluatorBase._handle_result
lxml.etree.XPathEvalError: Unregistered function

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.8/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<console>", line 1, in <module>
  File "/home/timmy/.local/lib/python3.8/site-packages/scrapy/http/response/text.py", line 117, in xpath
    return self.selector.xpath(query, **kwargs)
  File "/home/timmy/.local/lib/python3.8/site-packages/parsel/selector.py", line 260, in xpath
    six.reraise(ValueError, ValueError(msg), sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/six.py", line 702, in reraise
    raise value.with_traceback(tb)
  File "/home/timmy/.local/lib/python3.8/site-packages/parsel/selector.py", line 254, in xpath
    result = xpathev(query, namespaces=nsp,
  File "src/lxml/etree.pyx", line 1582, in lxml.etree._Element.xpath
  File "src/lxml/xpath.pxi", line 305, in lxml.etree.XPathElementEvaluator.__call__
  File "src/lxml/xpath.pxi", line 225, in lxml.etree._XPathEvaluatorBase._handle_result
ValueError: XPath error: Unregistered function in //img[matches(@alt,'mediamarkt','i')]