title: Problem in compiling java project in Netbeans
body: <p>I have a problem now :
  When I want to compile my project in Netbeans IDE I had this message error : </p>
  
  <pre><code>Problem: The project uses a class library called "toplink", but this class library was not found.
  Solution: Click Resolve to open the Library Manager and create a new class library called "toplink".
  </code></pre>
  
  <p>In fact I didn't change anything and it works fine before?</p>
  
  <p>What's the problem?</p>