ASterisk 1.8 manager cant connect from remote pc

Hi people

Yesterday i install version 1.8 RC3 over my AsteriskNOW 1.7 and everything works fine except I can not connect to the manager from a remote station, tells me

== Manager ‘marcos’ logged on from 10.2.20.193
== Manager ‘marcos’ logged off from 10.2.20.193
== Connect attempt from ‘10.2.20.193’ unable to authenticate

this is manager.conf

[general]
enabled = yes
webenabled=yes
port = 5038
bindaddr = 0.0.0.0

[marcos]
secret=marcos
read=all
permit=10.2.20.193/255.255.0.0

any ideas??
txs in advance