Execute hadoop 1.0.1 application in hadoop 2.6.0 cause Output directory not set execption

The application can run normally in Hadoop 1.0.1 but can't run in 2.6.0 even though adapt to use new mapreduce API.

org.apache.hadoop.mapred.InvalidJobConfException: Output directory not set.
at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:128)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:889)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1093)
at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:500)
at org.apache.hadoop.mapreduce.lib.jobcontrol.ControlledJob.submit(ControlledJob.java:336)
at org.apache.hadoop.mapreduce.lib.jobcontrol.JobControl.run(JobControl.java:233)
at java.lang.Thread.run(Thread.java:745)