Do you have the WePrint helper installed on your Mac/PC?

Is your iPhone using WiFi or 3G/EDGE?

What is the "Server Address" displayed in the WePrint window?
Server Address

What is the "Device Address" displayed when you tap the "i" button on the iPhone App home screen?
Device Address

Try turning off your firewall briefly to see if that solves the problem.
If it does, then you will need to add WePrint as an exception in your Firewall:
This is the page for Windows:
http://mobile.eurosmartz.com/winhelp.html

This is the page for Mac:
http://mobile.eurosmartz.com/machelp.html

The IP address starting 169., and a blank Router field in your iPhone's WiFI settings indicates that it is not correctly connected to your WiFi router.
Even though the iPhone has your password for your network it is not getting allocated a proper address.

Before you start, please make sure you have your WEP or WPA WiFi network key handy (you may need to consult your setup information).

1. On your iPhone Go to Settings -> General -> Reset -> Reset Network Settings -> Confirm. The iPhone will completely reboot
2. Now go to Settings -> WiFi and select your network, enter your WEP/WPA key and hit join.
3. Now tap on the blue arrow beside your network and the IP address should be similar to the Server Address on WePrint. The last digit should be different

Your iPhone/iPod doesn't appear to be in the same network as your WePrint server.
The IP addresses should be the same apart from the last digit.
Perhaps it is using 3G or is not connected to the same WiFi network as WePrint.
You can set up "Print via Proxy" to allow you to print..

Try also changing the WePrint port number in the WePrint Settings - Advanced tab.
Set the custom port number to 8081,8082,8083 etc.
Make sure you change the port on the iPhone Add WePrint screen too if it doesn't find it automatically.