How do I find out why a java class in oracle is INVALID -

i have java class. load oracle 11 this:

create or replace , compile java source named cubetester import java.io.printwriter; import java.io.stringwriter; ... etc 

oracle responds "statement processed" -- looks did things right.. when sql statement find it's validity this:

select object_name, dbms_java.longname(object_name), status user_objects object_type='java class' , dbms_java.longname(object_name) '%cubetest%'  order 1 

i this:

 object_name    dbms_java.longname(object_name) status  cubetester cubetester  invalid 

now went , checked every import have, , every 1 of them came valid. (except java.io.*, part of jdk assume that ok -- wrong?)

and yes, code works fine eclipse (and command line too)

how 1 debug this? problem doing apex (sql workshop), not have access box, can't use sqlplus or that. has single sql command or something.

any suggestions on how proceed?