title: Fields "Created" and "Modified" in Document Properties (PDF) were not displayed
body: <p>Currently I have merged many PDFs together to create one PDF together. I have added metadata information which includes two fields &quot;Created&quot; and &quot;Modified&quot; but as a result these fields still do not display information.
  Here's my source code:</p>
  <pre><code>import re
  import os
  import fitz
  from datetime import datetime
  
  def importMetaData(path):
      regex = r&quot;^r20ut(\d+)ej(\d+)$&quot;
      r_UM = re.compile(regex)
      extension = [&quot;.pdf&quot;]
      now = datetime.now() # current date and time
      date_time = now.strftime(&quot;%m/%d/%Y %H:%M:%S %p&quot;)
      print(&quot;date and time:&quot;,date_time)
      Number = &quot;&quot;
      for root, dirs, files in os.walk(path):
          for file in files:
              ext = os.path.splitext(file)[-1].lower()
              f_name = os.path.splitext(file)[0]
              if ext in extension:
                  if r_UM.search(f_name) is not None:
                      if root.endswith(&quot;thuan1&quot;):
                          Number = dictRNumber[&quot;code1&quot;]
                      elif root.endswith(&quot;thuan2&quot;):
                          Number = dictRNumber[&quot;code2&quot;]
                      else:
                          continue
                      inforPDF=fitz.open(os.path.join(root, file))
                      inforPDF.set_metadata({})
                      inforPDF.set_metadata(
                      {
                          &quot;producer&quot;: &quot;Microsoft® Word for Office 365&quot;,
                          &quot;author&quot;: &quot;Thuan&quot;,
                          &quot;modDate&quot;: date_time,
                          &quot;title&quot;: &quot;Data Analysis&quot;,
                          &quot;creationDate&quot;: date_time,
                          &quot;creator&quot;: &quot;Microsoft® Word for Office 365&quot;,
                          &quot;subject&quot;: Number
                      })
                      inforPDF.save(os.path.join(root, f_name+&quot;.pdf&quot;))
  </code></pre>
  <p>Image</p>
  <p><a href="https://i.stack.imgur.com/RhlGu.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RhlGu.jpg" alt="Image" /></a></p>
  <p>Could you please give me some advice?</p>