No result in published worksheet

edit

Hey guys..

I just can't find out what's the problem. When I am editing my worksheet everything works for this example from the wiki:

srg = srange(-4,4,1/10,include_endpoint=True)
@interact
def dualv(a1=slider(srg,default=1),a2=slider(srg,default=2), a3=slider(srg,default=-1),a4=slider(srg,default=3)):
    A1 = arrow2d([0,0],[a1,a2],rgbcolor='black')
    A2 = arrow2d([0,0],[a3,a4],rgbcolor='black')
    A3 = arrow2d([0,0],[a1,a3],rgbcolor='black')
    A4 = arrow2d([0,0],[a2,a4],rgbcolor='black')
    p1 = polygon([[0,0],[a1,a2],[a1+a3,a2+a4],[a3,a4],[0,0]], alpha=.5)
    p2 = polygon([[0,0],[a1,a3],[a1+a2,a3+a4],[a2,a4],[0,0]],rgbcolor='red', alpha=.5)
    A = matrix([[a1,a2],[a3,a4]])
    html('<h3>The determinant of a matrix is equal to the determinant of the transpose</h3>')
    html("$det(%s) = det(%s)$"%(latex(A),latex(A.transpose())))
    show(A1+A2+A3+A4+p1+p2)

But when I publish this worksheet, the plot is not evaluated/shown/rendered. The control-bars are here but not the graphics. I've checked the HTML-contend.. there is none.

<table border="0" width="100%" bgcolor="white">
  <tbody>
    <tr>
      <td valign="top" bgcolor="white" align="left">
        <pre></pre>
      </td>
    </tr>
    <tr>
      <td valign="top" align="left"></td>
    </tr>
  </tbody>
</table>

Does anyone know what's the problem here? And could anyone tell me how I can see a log of what the server got from the client and of what the server did in response?

Thank you for any help.