title: Adding an existing field to an existing FIX message
body: <p>I am trying to add the <a href="https://www.onixs.biz/fix-dictionary/4.4/tagNum_115.html" rel="nofollow noreferrer">OnBehalfOfCompID</a> field to the <a href="https://www.onixs.biz/fix-dictionary/4.4/msgType_8_8.html" rel="nofollow noreferrer">ExecutionReport</a> message for the Fix Protocol, however my code is throwing an error of <code>QuickFix.FieldNotFoundException: field not found for tag: 115</code> when attempting to retrieve the value of this new field.</p>
  
  <p>My DataDictionary is as follows:</p>
  
  <pre><code>&lt;message name='ExecutionReport' msgcat='app' msgtype='8'&gt;
  ...
   &lt;field name='OnBehalfOfCompID' required='N' /&gt;
  ...
  &lt;/message&gt;
  </code></pre>
  
  <p>I also manually modified our <code>FixLibV3.Messages.Fix50SP2.ExecutionReport.generated.cs</code> to include the OnBehalfOfCompID details:</p>
  
  <pre><code>/// &lt;summary&gt;
  /// Tag 115 of type STRING-&gt;StringField. Optional.
  /// &lt;/summary&gt;
  public Fields.OnBehalfOfCompID OnBehalfOfCompID
  {
      get
      {
          var v = new Fields.OnBehalfOfCompID();
          GetField((StringField)v);
          return v;
      }
      set { SetField(value); }
  }
  
  /// &lt;summary&gt;
  /// Tag 115
  /// &lt;/summary&gt;
  public void Set(Fields.OnBehalfOfCompID v)
  {
      OnBehalfOfCompID = v;
  }
  
  /// &lt;summary&gt;
  /// Tag 115
  /// &lt;/summary&gt;
  public Fields.OnBehalfOfCompID Get(Fields.OnBehalfOfCompID v)
  {
      GetField((StringField)v);
      return v;
  }
  
  /// &lt;summary&gt;
  /// Tag 115
  /// &lt;/summary&gt;
  public bool IsSetOnBehalfOfCompID()
  {
      return IsSetField(Fields.Tags.OnBehalfOfCompID);
  }
  
  /// &lt;summary&gt;
  /// Tag 115
  /// &lt;/summary&gt;
  public bool IsSet(Fields.OnBehalfOfCompID v)
  {
      return IsSetOnBehalfOfCompID();
  }
  </code></pre>
  
  <p>When I try and retrieve the value for <code>OnBehalfOfCompID</code> with</p>
  
  <pre><code> _executionReport.GetString(Fields.Tags.OnBehalfOfCompID);
  </code></pre>
  
  <p>or even with </p>
  
  <pre><code>_executionReport.OnBehalfOfCompID.getValue();
  </code></pre>
  
  <p>I get the error:</p>
  
  <pre><code>'_executionReport.OnBehalfOfCompID' threw an exception of type 'QuickFix.FieldNotFoundException'
  </code></pre>
  
  <p>During debug I can clearly see that the field <code>115</code>exists in the string representation of the message. How do I successfully pull the value from the message? What am I missing?</p>