Blackmagic Design TV Studio SD output from laptop

Hi,
I'm trying to mix 2 sd cameras (cony pd177) and a laptop output. i'm able to get cameras to the TV Studio using BMD analog to sdi converters. My laptop has an HDMI output port but i'm not getting the output to TV Studio. i've trying using different resolution settings but no use. It just show blue screen at ATEM TV STUDIO for laptop output. BTW i've tried changing cable and even laptop (DELL XPS Studio) but same result.

Any ideas please???

Kind regards
Harry