text: Q:
  
  D3 : can't call svg.selectAll("text") twice on a same SVG object
  
  I think my understanding of selectAll is wrong, 
  This jsFiddle should explain the problem
  http://jsfiddle.net/maxl/JY4hq/2/
  I have create a bar chart like follows : 
  svg.selectAll("rect")
             .data(dataset)
             .enter()
             .append("rect")
              //etc
  
  I add labels
          svg.selectAll("text")
             .data(labels)
             .enter()
             .append("text")
             .text(function(d) {return d})
              // etc
  
  then values that get should be displayed at the right end of the bars :
          svg.selectAll("text")
             .data(dataset)
             .enter()
             .append("text")
              // etc
  
  The problem is that the last addition of texts don't get added to the parent SVG
  node. I think my understanding of selectAll is deficient ...
  
  A:
  
  I have written a post explaining how selectAll and enter works. It will help in understanding the issue. 
  Here is the link: http://knowledgestockpile.blogspot.com/2012/01/understanding-selectall-data-enter.html?m=1
  If you want a quick fix, the following should work if there are no other elements 
  with the class labels and class values in your html document:
      svg.selectAll("text.labels")
         .data(labels)
         .enter()
         .append("text")
         .text(function(d) {return d})
          // etc
  
      svg.selectAll("text.values")
         .data(dataset)
         .enter()
         .append("text")
          // etc
  
  