title: Python Pandas indexing provides empty DataFrame error
body: <p>I am new to Python and trying to indexing and slicing of my data using Pandas in Python but it gives me an error of &quot;Empty DataFrame&quot;.
  Following are my python lines:</p>
  <pre><code>import pandas as pd
  from scipy import stats
  
  df = pd.read_csv(filename,delim_whitespace=True, header=None, names=['year','month','lat','lon','aod','toa','sfc'])
  df.set_index('year','month','lat','lon','aod','toa','sfc', inplace=True, drop=True)
  idx = pd.IndexSlice
  
  tmp = df.loc[idx[2011,3,10.0,30.0,:,:,:],]
  print(tmp)
  </code></pre>
  <p>This gives me the following error:</p>
  <pre><code>Empty DataFrame
  Columns: []
  Index: [(2011, 3, 10.0, 30.0, 1.031, 228.524, 987.44), (2011, 3, 10.0, 30.0, 0.28300000000000003, 202.205, 1036.77), (2011, 3, 10.0, 30.0, 0.45899999999999996, 214.261, 1054.85), (2011, 3, 10.0, 30.0, 0.35100000000000003, 201.296, 1064.03), (2011, 3, 10.0, 30.0, 0.15, 195.709, 1073.97), (2011, 3, 10.0, 30.0, 0.204, 201.37599999999998, 1061.8), (2011, 3, 10.0, 30.0, 0.39899999999999997, 195.92700000000002, 1041.49), (2011, 3, 10.0, 30.0, 0.612, 203.899, 1018.99)]    
  </code></pre>
  <p>These lines give me the results without slicing with Empty Dataframe error.
  I will grateful if someone points out the solution.</p>
  <p>Thank you</p>