Cannot connect to Home VPN PPTP

Hi there! My setup is as follows

OSX Mavericks on 2010 MacBook Pro
Comcast Business class ISP (both sides)

The network setup at home goes through comcast's modem, then through my WatchGuard X550e, then to the network. VPN is using PPTP

I have two computers I am using at work, the macbook pro and a windows 7 machine. I can connect to my home VPN just fine on the windows machine, but I get the error "A connection could not be established to the PPP server. Try reconnecting. If the problem continues, verify your settings and contact your Administrator"

Can anyone help me get connected?