Is it not possible to rebuild an INDEX online in Ora8i standard edition?

I want to rebuild an index but its always busy - I get ORA-00054: resource busy and acquire with NOWAIT specified.

So I attempted ALTER INDEX nnnnn REBUILD ONLINE and got the ORA- 00439 error.

I looked for the index name in v$locked_object view but its not there - the Table the index is based on is there, but not the index. Presumably a transaction has locked the table and thus the index too? (its the PK index for the table).

Do I just wait til the system's quiet?