Getting ClassNotFoundException even though jar is included in lib folder

In YARN, we are getting the below exception. The same is running fine in MRv1.The jar containing CSVReader.class in included in the lib folder.
Tried also setting the jar in HADOOP_CLASSPATH as well,but still the same exception.

13/12/31 09:26:37 INFO mapreduce.Job: map 0% reduce 0%
13/12/31 09:26:42 INFO mapreduce.Job: Task Id : attempt_1388462142258_0001_m_000003_0, Status : FAILED
Error: java.lang.RuntimeException: Error in configuring object
at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:106)
at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:72)
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:130)
..........
..........
Caused by: java.lang.NoClassDefFoundError: au/com/bytecode/opencsv/CSVReader
at com.tcs.nextgen.pe.wm.datagen.maptask.MPOCDataMapperNewest.configure(MPOCDataMapperNewest.java:56)
... 22 more
Caused by: java.lang.ClassNotFoundException: au.com.bytecode.opencsv.CSVReader
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)