The specified value of PGA_AGGREGATE_TARGET was not compatible with current settings of SGA_TARGET and MEMORY_TARGET/MEMORY_MAX_TARGET.
Set PGA_AGGREGATE_TARGET to be no more than the difference of MEMORY_TARGET/MEMORY_MAX_TARGET and SGA_TARGET.
Browse all solutions to database errors from Oracle, MS SQL or MySQL
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e0.htm