If:
- You have a broadband connection AND
- You are hosting the pictures on your own computer AND
- You have a router doing NAT in between the cable modem and your computer.
It's likely the router can't route the external (broadband) IP to your local IP.. it gets confused.
If this has all gone over your head, nevermind.. probably not your problem
If this sounds like your problem, let me know and I'll post more.