------------AWR report error-------------

Hi ,

After generating the AWR report on oracle  11.1.0.7.0 - 64bit  AIX Platform i get the following error and there is also no data found related to memory  also showing that

 "No data exists for this section of the report."

 WARNING (-20008)
ORA-20008: Missing Init.ora parameter timed_statistics

WARNING (-20008)
ORA-20008: Missing Init.ora parameter statistics_level

WARNING (-20008)
ORA-20008: Missing Init.ora parameter statistics_level

WARNING (-20008)
ORA-20008: Missing Init.ora parameter sga_target

WARNING (-20008)
ORA-20008: Missing Init.ora parameter pga_aggregate_target

WARNING (-20023)
ORA-20023: Missing start and end values for time model stat: background cpu time