Capturing Duplicates in an output file

I was trying out XSUM to capture the duplicates in a separate output file but it was failing with normal SORT.

With ICETOOL ,it works.

Here is the sample I created.

//DOIT EXEC PGM=ICETOOL                                          

//TOOLMSG DD SYSOUT=*                                            

//DFSMSG DD SYSOUT=*                                             

//IN DD DSN=U123557.ONLYDB.UUID,DISP=SHR                         

//OUT DD DSN=U123557.TEST.OUTPUT,DISP=SHR                        

//SORTXSUM DD DSN=U123557.TEST.XSUM,DISP=SHR                     

//TOOLIN DD *                                                     

SELECT FROM(IN) TO(OUT) ON(1,6,CH) FIRST DISCARD(SORTXSUM)       

/*