Can you please refer me to the exact XML that you are using. The best would be if you could do the following
1- In the command tree editor right-click the group and then select copy.
2- Reply to this forum post, click the code icon (button above the message entry text box with a # symbol on it), and then type ctrl-v to paste the code.
I guess you are using Frodo, so we will only need to change you actions to use xJSON softmute actions.
Please note that a prefix does not turn VC green. It only allows a command to execute when you are in standby mode. The prefix must be spoken at the beginning of a command, as part of the command. You can't just say the prefix and then wait. To do that you should just use the pay attention command. You could also get the pay attention command to lower you volume if you wanted, and restore the volume when you return to standby mode.