SAP Message 29161 - BOM & is locked by &

Procedure
You want to work on BOM &V1&. One of the following situations triggeredthis error message:
You are already working on the BOM in another session.
The BOM is currently being processed by user &V2&.
The BOM has just finished being processed, but the system has notposted it yet.

Procedure
Try to access the BOM again later.
If the BOM is locked over a long period of time, ask user &V2& why itis locked.