Help I Have This Error How I Can Fix It ?

[balius]

Description    Resource    Path    Location    Type
The project was not built since its build path is incomplete. Cannot find the class file for org.mmocore.network.IMMOExecutor. Fix the build path then try building this project    New folder (2)        Unknown    Java Problem
 

 

Description    Resource    Path    Location    Type
The type org.mmocore.network.IMMOExecutor cannot be resolved. It is indirectly referenced from required .class files    GameServer.java    /New folder (2)/L2-Core/src/com/l2j/gameserver    line 1    Java Problem
 

[snifi]

Client section. Sorry. ;)