Windows Vista At home and Windows XP at the office

hello,

I used www.no-ip.com to build a server for remote desktop to my work computer.

My computer at the office has windows XP pro.

My computer at home has Windows Vista Home Professional.

When I try to use remote desktop with a windows XP computer to connect to my computer at the office- i have no problem.

When I try to connect with remote acceess to my office computer with my Home Computer (vista)- it says that it cannot find the computer and I need to enter a IP address.

I have no problem logging in from a computer with Windows XP but for some reason logging into the computer with Vista does not allow me to do so. Please HELP!