Preview ATEM Mini doesn't work

Hi. I need a help!
I'm trying to view the ATEM Mini preview on a monitor. But, I connect the HDMI to the ATEM Mini output and it doesn't show anything. I've changed HDMI cables several times and it still doesn't work. Any suggestions from support? Thanks.
I'm trying to view the ATEM Mini preview on a monitor. But, I connect the HDMI to the ATEM Mini output and it doesn't show anything. I've changed HDMI cables several times and it still doesn't work. Any suggestions from support? Thanks.