Connection OK, but unable to send commands or receive informations

Hello,
I just installed Repetier host on my ubuntu 14.04.
My printer in a BCN3D+
I succeed in connecting repetier with the printer : com port detected and when Iclick on "connection", I can see "connected : default" botom left of my screen.
But thats all : no information about the printer (temp for ex) and no possibility to send an order to the printer. The orders remains buffered and are not sent.
I tried several speeds for the connection...
With the same printer, I tried Repetier on the same computer but with Windows XP and it works well.
Thank you for your help and excuse me for my poor english ;-).
Pascal.