Problems with package hierarchy

Question

If i create a simple package hierarchy like this:
-trial
- trial.subTrial
and if i put an abstract class on trial, i cannot extend it on package subTrial (a strange error occur, saying that i'm not overriding the abstract methods, when in fact i am) . But if i put everything on the same package it's no problem!!
I don�t know if this is a problem of the IDE (i'm using netbeans), i tried with a very simple example, outside of the project, to see if it was a problem with my code, and the same errors occurred, or if it's some hierarchy concept i'm violating.
Does anyone knows anything about this?

Answer 1

Nop, that's not the case!! As i said, i made a project just to try this.
This is the code of the only 2 classes of the project:
package trial;
public abstract class Trial {
abstract void function1();
abstract void function2();
void function3(){
System.out.println("BLA");
} // End of Trial Class
package trial.subTrial;
import trial.Trial;
public class SubTrial extends Trial{
void function1(){}
void function2(){}
}// End of SubTrial Class