hI,
It may have happened that you might have issued the check manually and not updated through FCH5, hence SAP would have allowed to reverse document through FB08.
We can reset the cleared items once check is issued through FBRA else we have to use FB08.
You are requested to check the Check information and see whether check has been issued or not. If not our interpretation is correct else revert with steps.
In short
1. FBRA - used to reverse / reset when check is issued whether manually or generated through system.
2. FB08 - used to reverse documents generated.
Hope, this solves your issue.
Regards,
Tejas