It's missing the org.jasperforge.jaspersoft.demo.PlSqlQueryExecuterFactory class. I'd check your relevant JAR to see if that class exists, if not I'd contact Jasperforge to see where its gone/what it should be replaced with.
Yes, it's true... but I've builded the project oraclestoredprocedure, I've copied the build/class folder to iReport one, I've added the classpath to the PlSqlQueryExecuterFactory class into the option of iReport but... still that error!
Ah OK, hmm there's no mention of this problem in the various docs for the project. Can you perhaps try building the project, creating a JAR for the single class file and then referencing that JAR in the classpath?