How to connect my Cisco 2500 series Router to my Linksys Router?

When I connects and configure them, the cisco can ping the linksys, and I can ping the cisco from my pc that is connected to my linksys, but if the cisco tries to ping back to my pc it fails, and I have my cisco using a static ip, but the static ip is not displaying in the DHCP client table in the linksys router???