Redmine

Hi everyone, I'm having this problem and I don't know if it's a misconfiguration or a bug, so I'm trying to get help here before reporting a bug.
I've setup a redmine installation on ubuntu 12.04 (either with redmine 2.4.1 downloaded from official site and with redmine 1.3.2 from ubuntu package) using passenger and apache.
I repeated some fresh installations with both versions and I created several new projects. I marked my user (the administrator) as manager of some project, developers of other projects and none for the rest of the projects.
In every case, everything works fine, except for the "new issue" function. When I try to add a "new issue" after filling the form, I see the page loading for a while (about 4/5 seconds) and then an "Internal Server Error" is returned to me. Moreover, I couldn't find anything in the logs (either the apache logs setted to "debug" and the rails log).
Can you help me?