Error from auditing

[Wantit Tangrugsasut]

I have the error at the console said

file system of audit file has 19% free space left! an attempt to switch to the backup file failed must specify a backup file now!

so I use audsys to create backup file.
The next time that auditing run, it switch to backup file right away(switch next to current)

Now my next file is empty and when the next auditing run it pop up the same error message at console again.

if anyone know how to fix this problem, please let me know

Thank You