Yes you have to assign the Device to a crosspoint -- does not matter what crosspoint just pick one (there is a Bug not sure when/if fixed yet that if no XPT assignment is made the CC won't actually send out the message).
Next/New Question based on your mention of xpression controlling something -- Are you sending commands to "two" things that are on the same Computer. As in are you sending RossTalk to XPression and DashBoard that is on the same PC? If so have you assigned a different IP PORT? You can not have both connections to the same IP address trying to use 7788. You would want to change the DashBoard to 7789 in the switcher config and the dashboard listener config.
#Carbonite