Some configuration parameters must be set if your log files are being managed by ASM.
These configuration parameters are:
The ASM user ID for asm_username must have sysdba permission. For Oracle 10g or 11g, set asm_username as follows:
asm_username="sys as sysdba"
Alternately, for Oracle 11g, you can set asm_username as follows:
asm_username="sys as sysasm"
See the Replication Agent Reference Manual.