Question : IGRP routing

Ok, trying to lab this problem using a simulator and i can't get the network to talk. basically i have  a 192.168.18.0/27 network  3 different routers, has to run igrp..not eigrp, which to me is dumb, but i configure all the interfaces and use the same AS number in all and set the networks.  Problem is even though i enter like 192.168.18.32 for a network, it just shows 192.168.18.0.  i can ping to the directly connected serial, but not to the other serial of the neighbor router or to the router on the other side.  really simple configs, i've attached, and if anyone has router sim, i can upload the rsm so you can see what i am talking about.. thanks for any help.

routerA.txt (1 KB) (File Type Details) 

router a

routerB.txt (1 KB) (File Type Details) 

router B

RouterC.txt (1 KB) (File Type Details) 

router C

Answer : IGRP routing

What is the exact version of your CCM .... we also had the same issue on 6.0 but we upgraded to 6.1.3 and now after the upgrade we haven't the same situation again