Have you added the "log" statement in the access-list that you want to see in the syslog.
Second what is your logging level (warn, info, notif)?
access-list id [line line-num] {deny | permit}{protocol}{source_addr} {source_mask}{destination_addr}{destination_mask} [log [[disable | default] | [level]]] [interval secs]]
PIX>logging config example:
PIX>enable
PIX#conf term
PIX(conf)#logg on
PIX(conf)#logg trap wa
PIX(conf)#logg host inside 192.168.1.x.y
Access-list Command reference:
http://www.cisco.com/en/US/products/sw/secursw/ps2120/products_command_reference_chapter09186a00801727a3.html#wp1067755
Logging Command reference:
http://www.cisco.com/en/US/products/sw/secursw/ps2120/products_command_reference_chapter09186a00801727a9.html#wp1028090
sincerely
Patrick