can't connect to PPTP Server via ubuntu router

[seng1978]

Hi guys
I google around and found no solution at all to my problem
I setup a PPTP(ubuntu) server at (I call the location OLDHOME)
At my NEWHOME I got Netgear wireless Router and i got one wireless and one
wired client connected to it.
The wireless client is MAC and the wired is a M$ PC.
Both connect to my VPN OLDHOME perfectly.
Now when I go to my OFFICE, where I got Ubuntu NAT Router setup,
I cant connect to my VPN OLDHOME at all.
With my M$ PC I get error 619 all the time.
I tried playing around Iptable, but no luck.
When I go back to my NEWHOME then everything works perfectly, so it has to
do something my OFFICE Linux Router.

MY NEWHOME is on IP 192.168.1.0/24
and so is my WORK.
OLDHOME IP 10.5.1.0/24

How do i configure my DANG ubuntu NAT to let through GRE47?
PLEASE HELP!