ZNY CTLR ISSUED LOA PRESCRIBED ALT OF FL260 FOR ZOB CTLR BUT FAILED TO RECOGNIZE AND CHANGE THE ALT IN THE DATA BLOCK (FL240) CAUSING AN OPERROR WITH TFC AT FL250.

Narrative

I CLBED AN ACFT (ACR X) TO FL260; WHICH IS THE LOA-PRESCRIBED ALT; PRE-COORD FOR ACFT DEPARTING MDT GOING W TO ZOB AND REQUESTING FL260 OR ABOVE. THE ACFT WAS ONLY REQUESTING FL240 AND THAT WAS THE 'HARD' ALT WHICH WAS XFERRED IN THE DATA BLOCK TO THE ZOB CTLR. THE OTHER ACFT WAS XING PATHS AT FL250. THE ZOB CTLR TOOK ACTION TO STOP THE CLB BUT SEPARATION WAS LOST. SUPPLEMENTAL INFO FROM ACN 669352: ACR X (THE CRJ1) CHKED ON CLBING WBOUND ON J80 OUT OF FL195 FOR FL260. ACR X'S DATA BLOCK SHOWED FL240 AS THE FINAL ALT. ACFT Y WAS NEBOUND AT FL250. I THOUGHT ACR X STATED HE WAS CLBING TO FL240. ACR X WAS CLBING SO SLOWLY THAT HIS DATA BLOCK SHOWED HIM LEVEL AT FL240 FOR OVER 45 SECONDS. WHEN THE DATA BLOCK SHOWED HIM ABOVE FL240; ACR X WAS ALREADY WITHIN 5 MI OF ACFT Y. I ASKED ACR X TO CONFIRM LEVEL AT FL240. HE SAID NEGATIVE; HE WAS CLBING TO FL260. I TURNED ACR X L TO A HDG OF 180 DEGS AND HAD HIM DSND BACK TO FL240. ONCE ACR X REACHED FL240; I RECLRED HIM ON COURSE. THE CTLR IN ZNY FROM WHOM I RECEIVED THE HDOF ON ACR X CONFIRMED THAT HE CLRED THE ACFT TO FL260 EVEN THOUGH FL240 WAS THE REQUESTED FINAL ALT.