No PAT from Higher Sec to Lower Sec interface

I am a bit at a loss here.

I have three networks on my pix: inside, outside and a dmz. I want to
have traffic from inside to the dmz bet masquerarded (visiable as a dmz
ip to the dmz boxes) and vica versa (dmz traffic to the inside should be
seen with an inside ip).

I have right now these nat sets.

nat (inside) 0 access-list inside_outbound_nat0_acl
nat (inside) 10 192.168.0.0 255.255.0.0
nat (bcc) 0 access-list dmz_outbound_nat0_acl
nat (bcc) 10 172.16.0.0 255.255.0.0

from both I can access outside so there the Masquerading works. but
inbweteen I see the others box IP instead of the masqueraded one.

eg from an inside box to dmz I do
#> telnet dmz_ip 21

and I see in the netstat -an view on the dmz box the inside ip
(192.168...) and not the PIX GW ip (172.16....).

Same with the other way around

So what can I do, to make this happen?