title: Getting a "The best overloaded method match for ... has some invalid arguments" error message
body: <p>I am having problems with the following code:</p>
  
  <pre><code>public class ClientGroupDetails
  {
      public DateTime Col2;
      public String Col3;
      public Int32 Col4;
  
      public ClientGroupDetails(DateTime m_Col2, String m_Col3, Int32 m_Col4)
      {
          Col2 = m_Col2;
          Col3 = m_Col3;
          Col4 = m_Col4;
      }
  
      public ClientGroupDetails() { }
  }
  
  [WebMethod()]
  public List&lt;ClientGroupDetails&gt; GetClientGroupDetails(string phrase)
  {
      var client_group_details = new List&lt;ClientGroupDetails&gt;();
  
      using (connection = new SqlConnection(ConfigurationManager.AppSettings["connString"]))
      {
          using (command = new SqlCommand(@"select col2, col3, col4 from table1 where col1 = @strSearch", connection))
          {
              command.Parameters.Add("@strSearch", SqlDbType.VarChar, 255).Value = phrase;
  
              connection.Open();
              using (reader = command.ExecuteReader())
              {
                  int Col2Index = reader.GetOrdinal("col2");
                  int Col3Index = reader.GetOrdinal("col3");
                  int Col4Index = reader.GetOrdinal("col4");
  
                  while (reader.Read())
                  {
                      client_group_details.Add(new ClientGroupDetails(
                          reader.IsDBNull(Col2Index) ? (Nullable&lt;DateTime&gt;)null : (Nullable&lt;DateTime&gt;)reader.GetDateTime(Col2Index),
                          reader.IsDBNull(Col3Index) ? null : reader.GetString(Col3Index),
                          reader.GetInt32(Col4Index)));
                  }
              }
          }
      }
  
      return client_group_details;
  }
  }
  </code></pre>
  
  <p>It is giving me the following error:</p>
  
  <pre><code>Compiler Error Message: CS1502: The best overloaded method match for 'Conflicts.ClientGroupDetails.ClientGroupDetails(System.DateTime, string, int)' has some invalid arguments
  Line 184: client_group_details.Add(new ClientGroupDetails(
  </code></pre>