WRONG ROUTING LOADED INTO THE OMEGA.

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LEAVING NAT TRACK C; GANDER CLRED US NA RTE 122. FLT PLAN HAD NA 128. MY COPLT LOOKED UP NA 122 AND CALLED OFF THE NEW WAYPOINTS WHILE I LOADED THEM IN OUR OMEGA NAV UNITS CHKING THE POS OF THE INTXN ON OUR NAV CHART. WHEN APPROX 10 MI FROM TUSKY INTXN; MONCTON ASKED 'ARE YOU PROCEEDING TO ALLEX?' I SAID 'NO; WE WERE RECLRED NA 122 AND ARE NOW OVER TUSKY.' MONCTON THEN HANDED US OFF TO ZBW WHO ALSO ASKED IF WE WERE GOING TO ALLEX. AFTER TELLING HIM WE WERE OVER TUSKY; HE GAVE US A SQUAWK CODE; AND AFTER IDENT; CLRED US DIRECT TO PVD; PLYMM 4 ARR JFK. BECAUSE I HAD FAILED TO DOUBLE-CHK THE NEW ROUTING WHEN IT WAS ASSIGNED; I TOLD MY FO 'LET'S CHK THE BOOK AGAIN AND VERIFY NA 122.' IT WAS HERE WE DISCOVERED OUR ERROR. WE HAD LOADED NA 120. BOTH RTES ARE THE SAME OUT OF CYMON TO BRIGG; THEN NA 122 GOES TO ALLEX AND NA 120 GOES TO TUSKY. ALTHOUGH MY FO HAD MADE THE MISTAKE OF MISREADING THE LINES IN THE BOOK; I FEEL THE CAUSE IS MY FAILURE TO VERIFY THE PROPER ROUTING BEFORE LOADING INTO THE NAV EQUIP.