No IP Address; can't connect to G4; WHY?

I recently went wireless with airport on my G5. Is that why I don't have a IP address and can connect to my G4 via ethernet. I want to switch photos from one computer to the other but can get them to see each other. Even tried with firewire, transfered the photos and then they weren't there. What's up? Anyone know?

Can you say a little more about your configuration? You know that PowerMacs don't have Airport (WiFi) built in I hope?

Does this help?

Hardware Overview:
Machine Name: Power Mac G5
Machine Model: PowerMac7,2
CPU Type: PowerPC 970 (2.2)
Number Of CPUs: 2
CPU Speed: 2 GHz
L2 Cache (per CPU): 512 KB
Memory: 2.5 GB
Bus Speed: 1 GHz
Boot ROM Version: 5.0.7f0

AirPort Card Information:
Wireless Card Type: AirPort Extreme
Wireless Card Locale: USA
Wireless Card Firmware Version: 405.1 (3.90.34.0.p18)

For those that may need to know the solution was fairly simple. Turn airport off and your computer will give you an IP address. I had to type it in the "connect to server" window of the second computer but connecting was easy after doing so.

Ok, if you have a mac over ethernet and one over wireless then you must have a wireless enabled router, or a wireless bridge.

You need to determine which side is failing, either wireless (most common) or ethernet (less common but very possible too). If your router works as an access point or router, the easiest way to do this is to open the network utility in both machines, and ping your router's address (it must be listed as the router or gateway address in your network config). If one of the machines fails to ping, that's where the problem is. And from then on it's different diagnosis paths.

No IP address

I'm very confused. Sometimes I have an IP address, sometimes I don't ! ? Could is be my server? I unfortunally live in Holland at the moment. Could that be a factor?

I have a G5 OS 10.4.9 (dual) and a G4 OS 10.3.9.
I have them connected with an ethernet cable. There is NO Router involved.
The G5 is connected to the internet via air port express.
The G4 is not connected to the internet and doesn't have an air port card.

Neither the G4 or G5 have a IP address listed in system pref under network but shouldn't I be able to connect my 2 computers anyway???

I would love to follow Blissful's suggestion about pinging but I do not know what that is. Please instruct me or suggest a article. Thanks