title: AttributeError: 'DataFrame' object has no attribute 'value_counts'
body: <p>I've started using pandas this week so pardon me if I'm asking a really obvious question. I am trying to get pandas to loop through all the sheets in my Excel wb to extract a specific column, column F for counts of occurances via value_counts.</p>
  
  <p>Previously I used value_counts and typed in the specific name of the worksheet and it worked in pulling out the value count of that 1 sheet. However, the minute I replaced the sheet name to df1, it stops working.</p>
  
  <pre><code>df = pd.ExcelFile("filepath.xlsx")
  for df1 in df.sheet_names:
      df2 = pd.read_excel("filepath.xlsx", sheet_name=df1, usecols="F")
      df2.dropna(inplace=False)
      print (df2.value_counts())
  
  </code></pre>
  
  <p>I expect the output to be the unique values and their occurance numbers but it returns:</p>
  
  <p>AttributeError: 'DataFrame' object has no attribute 'value_counts'</p>
  
  <p>Can somebody please help me?</p>