title: sum of a column : Pandas .sum() returns 0.0
body: <p>I am trying to sum values of columns from a dataframe using <code>.sum()</code> with pandas. However, pandas returns '0.00' for all columns that have a datatype of 'float64'. It seems to be working fine for columns set as integers.</p>
  <p>here is what I have tried so far:</p>
  <pre><code>df = pd.read_csv(csv_file, delimiter=';')
  df = df.apply(pd.to_numeric, errors='coerce').fillna(0) *#I want to convert values to numeric*
  print(df['UE'].dtype) *#I print dtype of a column I am interested in to check if pandas converted as requested*
  print(df.sum(skipna=True)) 
  </code></pre>
  <p>The line <code>df.sum(skipna=True))</code> returns 0.00 for every columns set as float64.
  For column 'version dossier', it returns the correct sum which is 271.0. (See joined photo).</p>
  <p>Here is what the console gives me:</p>
  <p><a href="https://i.stack.imgur.com/CDDiQ.png" rel="nofollow noreferrer">Console results</a></p>
  <p>Does anyone has an idea why this is hapenning?</p>