[Samba] wins across two networks

[Hernán Agretti]

I have two networks connected via ipsec with openswan. Each network
contains one samba server managing one workgroup each one. The network
structure is the following one:

Network 131.0.0.0/16--Samba: 131.0.0.106 (workgroup groupa) ---
200.x.x.x ----internet----- 64.x.x.x ---- Samba: 192.168.1.1
(workgroup groupb)--Network 192.168.1.0/24

Machines in groupa (network 131.0.0.0/16): pc3 (131.0.0.2, windows),
avda1 (131.0.0.106, linux samba)
Machines in groupb (network 192.168.1.0/24): pc01 (192.168.1.2,
windows), rqta1 (192.168.1.1, linux samba)

Server 131.0.0.106 is a WINS server for both networks. Each client in
both network points wins server to 131.0.0.106.

The problem is that I can't browse the workgroup in the other network.
If I put \\pc01 or \\rqta1 on network neighborhood (pc01 and
rqta1=groupb) from pc3 (groupa) I can see the shares (it's ok). Also I
can see \\pc3 and \\avda1 from pc01. This means WINS works fine.
But I can't browse the list of machines of the other network. For
example: in pc01 I can't see the list of machines of groupa. In pc3 I
can't see the list of machines of groupb.

#----smb.conf (131.0.0.106)
workgroup = groupa
wins support = yes
domain master = yes
local master = yes
preferred master = yes
remote browse sync = 192.168.1.1
remote announce = 192.168.1.1
name resolve order = wins bcast
security = share

#----smb.conf (192.168.1.1)
workgroup = groupb
wins server = 131.0.0.106
wins proxy = yes
domain master = yes
local master = yes
preferred master = yes
remote browse sync = 131.0.0.106
remote announce = 131.0.0.106
name resolve order = wins bcast
security = share

I also tried without remote browse sync and remote announce, also
security=user, also without domain master in groupb.
I guess WINS works fine, because it can resolve any name in both
networks, but why I can't  browse?