First, there seems to be a mismatch in library names. Your agent code contains a line Use "jprova",
but then later in your post you are writing that the ciaociao class is in a library named "ciao".
Second, there's a limitation mentioned in the chapter on LS2J in Designer help: "LotusScript calls to Java script libraries are limited to native Java, and can not include calls to the LotusScript back end." The wording seems a bit off the mark -- I assume they really mean Notes/Domino back end. Whatever, I can confirm from my own experience that one cannot use, for example, AgentBase through LS2J, which you are trying to use in your example.
calling java from lotuscript with p... (Marco Tiraferri... 2.Aug.12)
Feedback response number JSAK8WSRBV created by Jochen Sack on 08/02/2012
. . A few observations (Jochen Sack 2.Aug.12)