title: KeyError When Slicing Dataframe
body: <p>My code looks like:</p>
  
  <pre><code>d = pd.read_csv('Collector Output.csv')
  df = pd.DataFrame(data=d)
  dfa = df.copy()
  dfa =  dfa.rename(columns={'OBJECTID': 'Object ID', 'test_no': 'TEST #', 'retest_no': 'RETEST #',
                          'tester': 'TESTED BY', 'date': 'DATE', 'proj_no': 'Project Number',
                          'test_elev': 'TEST ELEVATION', 'curve_no': 'CURVE #', 'curve':
                          'Curve Description', 'dry': 'Dry Maximum Density (pcf)', 'opt': 'OPT. M.C.',
                          'Material Type': 'Material Type', 'AC Thickness': 'AC Thickness', 'AB Thickness': 'AB Thickness',
                          'Wet In-place Density, pcf)': 'Wet In-place Density (pcf)', 'inplace_mo': 'FIELD M.C.',
                          'comp_dryde': 'DRY DENSITY', 'relative_c': 'R.C.', 'addl_notes': 'NOTES',
                          'material_t': 'Material Type', 'wet_inpac': 'Wet In-place', 'comp_dryde': 'comp_dryde', 'relative_c': 'relative compaction',
                          'GlobalID': 'GlobalID', 'GlobalID_2': 'GlobalID 2', 'x': 'EAST', 'y': 'NORTH'})
  
  
  writer = pd.ExcelWriter('Test Test.xlsx', engine= 'xlsxwriter')
  dfa.to_excel(writer, sheet_name='Output')
  writer.save()
  
  #Slice the dataframe to get the desired columns by their 'name'
  dfb = dfa[['TEST #', 'DATE', 'TESTED BY', 'NORTH', 'EAST', 'TEST ELEVATION', 'CURVE #', 'OPT. M.C.', 'FIELD M.C.', 
            'DRY DENSITY', 'R.C.', 'RETEST #', 'NOTES']] 
  </code></pre>
  
  <p>When I run it, I get a KeyError that reads ['DRY DENSITY' 'R.C.'] not index. I varified that the names are correct for the columns in the .csv. Why are these two columns giving an issue?</p>