you probably have not set up the URL -> siteaccess translation correctly. See this doc: http://ez.no/developer/ez_publish_3/documentation/installation_and_configuration/configuration/site_access
You need to write your siteaccess rules in a way that the first part of the URI translates into the siteaccess and the rest to the module + paramenters.
but, in the public site, when I use http://mysite/en and http://mysite/sl only the italian version is shown.... have you got any idea to solve the problem?
then you should make site.ini for each site, lets say for italian :
settings/siteaccess/it/
[RegionalSettings]
Locale=ita-IT
HTTPLocale=it ContentObjectLocale=ita-IT