title: using data not sorted (nearmrg)
body: <p>I am trying to use <code>nearmrg</code> on my data files and I keep getting the same error: </p>
  
  <blockquote>
    <p>using data not sorted</p>
  </blockquote>
  
  <p>As I wanted to break down the problem I used very simple test data instead of my real data and the error message still shows up. Now I have the following:</p>
  
  <p>Master.dta:</p>
  
  <pre><code>Group   Date
  A   15.01.2012
  A   15.02.2012
  B   15.01.2012
  B   15.02.2012
  C   15.01.2012
  C   15.02.2012
  </code></pre>
  
  <p>Using.dta:</p>
  
  <pre><code>Group Date SVarOfInterest1 SVarOfInterest2
  A 01.01.2012 1 201
  A 15.01.2012 2 202
  A 03.02.2012 3 203
  A 23.02.2012 4 204
  B 03.01.2012 11 211
  B 19.01.2012 12 212
  B 03.02.2012 13 213
  C 20.01.2012 21 221
  C 25.01.2012 22 222
  C 04.02.2012 23 223
  C 03.01.2012 24 224
  </code></pre>
  
  <p>This is the code:</p>
  
  <pre><code>nearmrg Group using Using.dta, nearvar(Date) genmatch(SourceDate) lower
  using data not sorted
  r(5);
  </code></pre>