Question on memory_target:11g

Hi,
Alert log of my 11.2.0.3 DB has following entries.

WARNING: Granules of pga_aggregate_target 300 cannot be more than memory_target (302) - sga_target (0) or min_sga (11)

Here are my memory settings

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target                 big integer 0


NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
memory_max_target                    big integer 19328M
memory_target                        big integer 19328M

Could some one throw some light and what action needs to be taken here?

Regards
Rajeev