Cipher not working

Platform:Windows

ISP:cpe-173-175-124-159.satx.res.rr.com

Type of Internet Connection:CATV

Internet Connection Speed:11.49Mbps

Date & Time:12/15/2017 18:23 CST

Frequency:
Always

Character Name:
Shakezilla

Race:
Hume F

World:
Leviathan

Main Job:
Thf 99

Support Job:
Dnc

Area and Coordinates:
Port Bastok K-7

Party or Solo:
Solo

NPC Name:
Clarion Star

Monster Name:
None

Steps:
1. Select Clarion Star
2. Select Trade
3. Attempt to trade Cipher: Koru-Moru
4. Nothing happens
5. Every other Cipher works perfectly but not Koru-Moru

Verify that you do not already know the spell. There are several sources for that cipher in particular, including an RoE questchain and Alter Ego Extravaganzas. Whichever way you got the current cipher item, there's a very good chance that you had already learned it from the other way and forgot.