Big picture:

3 PCs(A, B, C)
All connected via DLink Wireless Router
A is running a server (java process). Tank Simulation Module
B is running a client (java process). Tank AI.
C is running Cain.

Ultimate goal: Communication between A nd B needs to be modified. I would like to have control over what is sent to the server(A) from B. This could include MITH attack with APR.The data is XML. I'm decent on the Java side so I could write a parser which would handle the modification of the data from B to the server during the MITM attack.

Current problem:

Installed Cain on PC C. Clicked on "Sniffer" tab. Clicked on "Add to List". Clicked OK on the "Add MAC Address" window. Used defaults(192.168.0.1 is my routers IP), and nothing is found. I connect to the Router(via browser) and notice PC C(192.168.0.101) and PC A(192.168.0.102) in the Routers "Client List"(PC B is getting a fresh OS install as I type). Point is, I would think Cain should pick up the router and PC A.

Any help would truly be appreciated.