Effect of child build.xml over parent build.xml file

[Harish Tiruvile]

Hi all

I am having one complete project ..where i am having parent directory say "PAR".Inside Parent directory i am having build.xml file(along with .class files).
Inside PAR directory i am having two more directory say "CH1" & "CH2".Inside both child directory i am having separate build.xml file(along with .class files).

Problem:: I am having problem in building build.xml inside PAR directory.
I can build two child succesfully by using their respective build.xml file...But when i tryed to build xml file in PAR directory it is giving error

"
BUILD FAILED
E:\share\Server_Operations\clvserv\build.xml:72: Could not launch ln: java.io.IO
Exception: CreateProcess: ln -s XXXX.jar E:\share\Server_Operations\clvse
rv\jars/XXX.jar error=2

"

I have made some modification in java file present in child Directory "CH1"..i can compile the class present in "CH1" using ant....but parent build.xml file is giving error(But i have not modified anything in Parent directory,so)..
So,is it good to replace only child directories JAR file in server...is it required to compile from parent directry?