html:image does not call the setter-method of the form

[Friedli Beat [UFA AG Her]]

Title: html:image does not call the setter-method of the form

In a jsp Form this code works works perfect:
<html:submit property="editPos" > Position<%= val %> </html:submit>

Now I decided to use an image instead of a button like this:
<html:image property="editPos" src=""graphics/editWarenkorb.gif"" value="Position<%= val %>" />

The generated Code looks fine to me:
<input type="image" name="editPos" src=""graphics/editWarenkorb.gif;jsessionid=F3C57101544373C1913436E0277103C7"" value="Position0">

But the value 'Position0' is never filled up in the Formbean as the setter-method never is called. And I know, that the Formbean and all works correct as it works fine withe the submit-Button. Is my html:image Tag not good?

Thanks for any help or idea

Beat Friedli