Decives connected on wireless unreachable

Hello,

I am having the following problem with devices that are connected to my home network through a linksys router:

On the wireless router two laptops connect (one Windows 7, one Apple) and one wireless printer.
We have several computers and servers that are connected t the network by cables.

All devices connected by cable can see and reach all other devices, including the ones connected wireless.
All devices connected wireless can see and reach all devices connected by cable, but none of the other devices that are connected wireless.

It's the printer that causes us most trouble, because we are unable to reach it and thus unable to even install it on either of the laptops.
We can install the printer and use it wireless when we connect the laptop with a cable, but soon as we plug out the cable and connect through the router the printer becomes unreachable again.

We tried disabling all firewalls, we tried DHCP and static IP addresses. We tried calling Cisco and came to the conclusion that devices that are connected on the same router should be able to see each other, but they don't.
I would very much appreciate all help in this matter.