VirtualBox works but VMware doesn't

I have identical applications on identical guests (WinXp) connecting to the same DB on a linux host. On VirtualBox, this connection is established by entering the server address as the default gateway 10.0.2.2. In VMWare, the default gateway 172.16.212.2 and the connection fails to establish. Why is this? What tools can I use to investigate further ?

Thanks