Bad reception: Time Capsule --> Mini

I recently got a Time Capsule (it´s beautiful) and it works fine with my iMac but my Mac Mini gets zero in reception, and it´s even closer than the iMac.

How is that? I can connect to the TC from my Mini and change settings, channel etc but I cant use the internet.

I think it has to do something with my Airport-settings. I switched from a "regular" router to the TC. Do I have to "empty" Airport or something?

Is the iMac wireless or on ethernet?
Are both on same OS Tiger or Leopard?
Did u change settings on Mini while it was connected wirelessly?
In Sys Prefs/Network do/can u have a green light for Airport on both mini and iMac?

Problem solved. I just had to update my DHCP in the Network-settings and now I get connection.

I run Leopard on both machines and they are both wireless.