Hello Juan,
The HTTP error code 403 means forbidden, i.e. you are trying to access an SICF node that is not activated. You can check the URL called and see whether the service is activated.
For printing via WEBGUI, please follow SAP note 771683 - as I believe you are using a release 7.x.
About the limitations of frontend printing via WEBGUI, you can read SAP note 314568.
Kind regards,
Cris