Hello,
it seems that i be to stupid to get this to work 
the cromecast binding and the voice Mary Text-to-Speech is installed and i use openhab 2.3
here is my thing config:
chromecast:audio:schlafz [ ipAddress=“192.168.188.54” ]
chromecast:audio:office [ ipAddress=“192.168.188.53” ]
chromecast:audio:wohnz [ ipAddress=“192.168.188.52” ]
chromecast:audio:kazi [ ipAddress=“192.168.188.51” ]
/* Chromecast Audio Group - this works with the Google Home Mini */
chromecast:audiogroup:house [ ipAddress=“192.168.188.54” ]//, port=8009]//42576]
if i set the port to 42576 i get the following message:
chromecast:audiogroup:house’ changed from ONLINE to OFFLINE (COMMUNICATION_ERROR): Verbindungsaufbau abgelehnt (Connection refused)
if i use the port 8009 / or no port only one of my four google mini talks to me
in my rules file i use this command :
say(“test nachricht”, “marytts:bits1hsmm:deDE”, “chromecast:audiogroup:house”)
can someone explain me what i do wrong here ?
Thanks for your help.