LogMiner does not work when trying to connect to an ASM Instance.
From Oracle: Automatic Storage Management (ASM) is a feature in Oracle Database 10g that provides the database administrator with a simple storage management interface that is consistent across all server and storage platforms. As a vertically integrated file system and volume manager, purpose-built for Oracle database files, ASM provides the performance of async I/O with the easy management of a file system. ASM provides capability that saves the DBAs time and provides flexibility to manage a dynamic database environment with increased efficiency.