LXDE not starting "No screens found" but it's connected to my TV

I’ve just set up a new DietPi Instance, I’ve added LXDE but when I try startx I’m just getting an error about no screens found then it says

unable to connect to X server: connection refused

. The Pi is connected to my TV via HDMI.

At first when I looked in display options it said my resolution was 0x0 (even though I was viewing that on my TV) I’ve tried setting it to 1080p and 720p but after each reboot when I try startx I get the same error.

Is there something I’m missing?

are you trying this as root user?