title: Formula Excel find a Sheet by his index
body: <p>Hy everybody.
  I'm trying to control the value of some cells through a reference page …</p>
  <pre><code>'On &quot;TRAITEMENT&quot; sheet
  =NB.SI('refSheet'!A:A;'MyFirstPage'!I3)
  </code></pre>
  <p>So far so good.
  However the name of the page which contains the cell to be checked ('Myfistpage') is not sure. It can change his name and some new sheet can appear between my pages.</p>
  <p>I am sure, however, that my maximum page allowed is 15 and that they must all be processed.
  I would therefore like to do a treatment for each page according to their index.</p>
  <p>I try this code:</p>
  <pre><code>=NB.SI('refSheet'!A:A;feuil1!I3)
  </code></pre>
  <p>But the answer is always 0 regardless of the control performed ...</p>
  <p>At all, I had to find a method to select a pages without using his name.</p>
  <p>Thank all in advance for your answers.</p>