Could not load definitions from resource org/tigris/subversion/svnant/svnantlib.xml. It could not be found

I got in to this problem when i was building an application using ant. I googled for this error and found several solutions/reasons for this problem, but none of it solved the problem for me. Though i was having svnant.jar in the custom ant directory and i have exported ANT_HOME properly, i was getting this error. Then on further debugging i found that the system already had ant installed in it and it's path is taken as the ANT_HOME, exporting the ANT_HOME manually in the shell didn't override it. Then found there is already a FAQ describing this "I installed Ant 1.6.x and now get java.lang.InstantiationException: org.apache.tools.ant.Main"  in http://ant.apache.org/faq.html. Then i used ant --noconfig to stop sourcing of the ant.conf file. This solved the problem. Though the solution is simple, it was difficult to find the cause of the problem, as i used the same custom ant and build scripts in three boxes, whereas in other two boxes it worked fine and failing in one box was a surprise.