spark error when distinct on more than one cloume

[wan...@testbird.com]

sql:SELECT app_id,COUNT(DISTINCT app_id, macaddr) cut from object group by 
app_id 

Error Log
14/08/19 17:58:26 INFO MemoryStore: Block broadcast_0 stored as values to 
memory (estimated size 158.6 KB, free 294.7 MB)

Exception in thread "main" java.lang.RuntimeException: [1.36] failure: ``)'' 
expected but `,' found



SELECT app_id,COUNT(DISTINCT app_id, macaddr) cut from object group by app_id

                                   ^

        at scala.sys.package$.error(package.scala:27)

        at org.apache.spark.sql.catalyst.SqlParser.apply(SqlParser.scala:47)

        at org.apache.spark.sql.SQLContext.parseSql(SQLContext.scala:70)

        at org.apache.spark.sql.SQLContext.sql(SQLContext.scala:150)

        at com.testbird.sparkapi.APILearn1$.main(APILearn1.scala:30)

        at com.testbird.sparkapi.APILearn1.main(APILearn1.scala)

        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

        at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

        at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

        at java.lang.reflect.Method.invoke(Method.java:606)

        at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:292)

        at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:55)

        at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
any one can help me , thanks