Nikon Issue

[Deepblue12]

I've got my Nikon D3300 connected to a Skywatcher 72ED. When selecting liveview i get an error "Cannot start live view at current settings or under current conditions"

I've selected Manual, Bulb, ISO800 and gone through all the Menu options but it still doesn't work.

Has anyone come across this before and can help or advise 

Thanks

 

[Deepblue12]

additional info.

Missed out one important part. I'm running the camera via a RPi and Kstars. If i disconnect the USB then Liveview works but i need the connectivity to control the camera.