If I roslaunch webui, roslaunch my talker_listener.launch file manually, and then run the app in webui it works, but if I just roslaunch webui and try to run my app, the chatter topic is not subscribed to. I figure this is because the launch file isn't being executed. It's probably because I have my launch_file path set wrongly.

launch_file: sample_application/opt/ros/wu-ros-pkg/sample_application/talker_listener.launch    

the wiki details that this line should be the package_name/launch_file_path.

Possibly relevant: when I roslaunch webui webui.launch and go to different pages in webui, the terminal prints warnings:

[WARN] 1279308554.052159: Cannot subscribe to /texas_power/state