title: Why is Filtergroup (-1) in Navision Page OR filtering on page level not working
body: <p>Is it possible that filtering with an OR condition (using <code>FILTERGROUP(-1)</code>) isn't working on page level`?
  and if so, why isn't it working?</p>
  <p>I'am new to MS-Navision and i try to understand the underlining programming of it.
  in MS-Navision Cronus-AG DB i created a Page based on the Customer Table. In the Customer Table i added two fields ( <code>Datefield Date</code> and <code>CodeField</code> Integer).  The created Page should only display Customers where <code>Datefield</code> OR  <code>codefield</code> is empty. I used two empty  Variables called</p>
  <pre><code>date Date 
  codefield Code
  </code></pre>
  <p>I Tried to use the following Code in the <code>OnOpenPage</code>-Trigger:</p>
  <pre><code> CLEAR(date);
   CLEAR(c20);
   
   FILTERGROUP(-1);
   SETFILTER(DateField, '%1', date);
   SETFILTER(CodeField20Old, '%1', c20);
   FILTERGROUP(0); // tried to remove this line, still not working
  </code></pre>
  <p>But no filter is set, especially not in the OR-Filter condition. How ever, if i use the same code snipped in a Codeunit, it is working the right way. And if i change <code>FILTERGROUP(-1)</code> to <code>FILTERGROUP(2)</code> a filter is set (with an AND-Condition).</p>
  <p>Can anybode explain me this bevhavior?</p>