CPR Y DSCNT TO OCCUPIED ALT HAD LTSS FROM SMA X. SYS ERROR.

Narrative

SMA X 130 SEBOUND OVERFLYING CSG AND CPR Y NBOUND FROM TLH DIRECT ARNCO LNDG MGE. I HAD 5 ACFT HOLDING AT LGC TO LAND ATL AND SMA X OVERFLT. CPR Y WAS GIVEN CLRNC TO 140 AND TOLD TO EXPEDITE; AND I EXPLAINED MY INTENT WAS TO GET HIM UNDERNEATH THE HOLDING PATTERN AT LGC. I WAS VECTORING 2 OF THE ARRS OUT OF HOLDING AND TOLD AN ACR; WHO WAS HDG 230; CLRED DIRECT LGC. HE MADE A L TURN TO LGC IN LIEU OF A R TURN AND HE WAS AT 140 AND QUICKLY BECOMING TFC FOR CPR Y. I LOOKED AT THE DATA BLOCK ON SMA X AND FOLLOWED THE LEADER LINE TO THE TARGET AND ESTABLISHED HIS POS AS NW OF CSG. I WENT TO CPR Y; WHO WAS OUT OF ABOUT 170; AND DSNDED HIM TO 110 AND TOLD HIM TO EXPEDITE. THE CONFLICT ALERT WENT OFF WITH CPR Y OUT OF 142 DSNDING 3 1/2 MI NNE OF SMA X. I TOLD CPR Y TO MAINTAIN 140 AND FLY HDG 060 DEGS. IT WAS TOO LATE. I HAD OFFSET DATA BLOCKS ON ALL ACFT 2 LENGTHS IN LIEU OF STANDARD 1 LENGTH. WHEN I LOCATED SMA X I FOLLOWED THE DATA BLOCK LINE TO THE WRONG TARGET; BUT WAS UNAWARE OF MY ERROR UNTIL THE CONFLICT ALERT ACTIVATED.