Here is a link to the XC18A wiki page.
http://kbase.x10.com/wiki/XC18Ahttp://kbase.x10.com/wiki/Wireless_CamerasYou probably have the correct receiver. Look at the links above and verify the camera is set to the correct channel. Probably a switch under a small rubber hole plug.
The power supply for the cameras have an X10 address set by the House Code and Unit Code Dials.
They work in groups of four. Unit Code 1-4,5-8,9-12 and 13-16.
Send an x10 On to one of the four. The other three in the group go Off. As the receiver can only process one RF signal at a time. Have more than one On they will interfere with each other.
You will need an X10 power line sender to control them.
Did you get any camera remotes? Then you could use a Transceiver to process the remotes commands to the power line.