[Serusers] Load Pa module problem

[Xudong Ni]

I am a beginner and just set a SER server,  the SER server
looks working fine, the SIP-communicator can register it.
The SER Version is 08-12-0.

But when I tried to load the pa module, there is always a problem:

I have set the following modparams in my ser.cfg:

loadmodule "/usr/lib/ser/modules/pa.so"
.....

modparam("pa", "default_expires", 60)
modparam("pa", "pa_domain","rocksteady.cs.fiu.edu")
modparam("pa", "use_db", 1)
modparam("pa", "db_url", "mysql://ser:heslo@localhost/ser")

The ser always failed at modparam("pa", 
"pa_domain","rocksteady.cs.fiu.edu").

Have I missed something? Could anybody help me how to find
document about Pa module? how to load pa module at ser.cfg?
I have done a lot search, but the documentation is really hard to find.

Thanks a lot

Xudong