Can't see cards in live server game

I’m the author of the war board game about WW2: Apocalypse: World War II Europe 1939-1945

I designed a game module, and I was just conducting a live playtest on the VASSAL server.

Everything seemed fine until we opened one of the windows containing a board and a deck of cards.
The deck was set up to give random cards as you drag them out of the deck, and to reveal them with a flip command.

The other person couldn’t see any of the cards I was drawing or revealing, and I couldn’t see any that he was drawing or revealing.

Nothing seemed to work.
I need your suport, because I do not know what to do.

The module you can find in link:

Thank you for your help !

Best regards,