pg_stat_all_tables shows all 0's

Hi,

When I query the pg_stat_all_tables view all I get back is 0's. How
can I tell if the statistics collector is running? I have the param's
set in my config file.

#
# Access statistics collection
#
stats_start_collector = true
stats_reset_on_server_start = true
stats_command_string = false
stats_row_level = false
stats_block_level = false

thanks
michael