You have the wrong command. I'm pretty sure that -1 will be the second video device, not first. Should be -0.
Second, "d" is disable. You want to "e" to enable or "D" for Digital enable.
The ports will be LVDS for laptop screens, VGA for analog 15 pin, HDMI, or DVI. You can use multiple video= lines to enable multiple ports. So a laptop screen plus HDMI would be :
video=LDVS-0:D video=HDMI-0:D
You should try e instead of D if it fails, or try -1 instead of -0 as I may be wrong. Xrandr shows these as -0 based, not -1.