Junit not found in Ant's CLASSPATH

[Rami Sawas]

I keep getting the following error even though I put
junit.jar in my %ANT_HOME%/lib directory:
Junit not found in Ant's CLASSPATH
at org.apache.tools.ant.taskdefs.Exit.execute(Exit.java:74)
at org.apache.tools.ant.Task.perform(Task.java:217)
at org.apache.tools.ant.Target.execute(Target.java:184)
at org.apache.tools.ant.Target.performTasks(Target.java202)
.... ....
at org.apache.tools.ant.Main.main(Main.java:176)

Can you please help me.