HIVE: Execution Error, return code [-101] (unknow error) from org.apache.hadoop.hive.ql.exec.FunctionTask

I write a UDF as flow:

  package com.test;
    import org.apache.hadoop.hive.ql.exec.UDF;
    import org.apache.hadoop.io.Text;

    public class Lower extends UDF {
        public Text evaluate(final Text s) {
            if (s == null) {
                return null;
            }
            return new Text(s.toString().toLowerCase());
        }
    }

then I export a jar(udftest.jar) of this test project by eclipse. After that I add jar udftest.jar in hive:

hive command: add jar udftest.jar;   
hive command: create temporary function my_lower as 'com.test.Lower';
hive command: Executing command:  create temporary function my_lower as 'com.test.Lower'

Execution Failed!

Failed: Error occurred during execution.
Detail message: FAILED: Execution Error, return code [-101] (unknow error) from org.apache.hadoop.hive.ql.exec.FunctionTask

I don't know why! I search the internet but not deal with this problem!