added entry in the faq

Documentation.html

@@ -4359,6 +4359,11 @@ chmod o+rwx tmp
         <dd>phpMyAdmin with version</dd>
 </dl>
 
+<h4 id="faq6_28">
+    <a href="#faq6_28">6.28 Why can't I get a chart from my query result table?</a></h4>
+
+<p> Not every table can be put to the chart. Only tables with one, two or three columns can be visualised as a chart. Moreover the table must be in a special format for chart script to understand it. Currently supported formats can be found in the <a href="http://wiki.phpmyadmin.net/pma/Devel:Charts#Data_formats_for_query_results_chart">wiki</a>.</p>
+
 <h3 id="faqproject">phpMyAdmin project</h3>
 
 <h4 id="faq7_1">

tbl_chart.php

@@ -169,6 +169,12 @@ $url_params['reload'] = 1;
     </td></tr>
     <?php } ?>
 
+    <tr><td colspan="2">
+        <p>
+            <?php echo __('Note that not every result table can be put to the chart. See <a href="./Documentation.html#faq6_28" target="Documentation">FAQ 6.28</a>'); ?>
+        </p>
+    </td></tr>
+
     </table>
 
 </fieldset>