First, check whether Live View works normally in daylight or on other bright subjects. If it does, the issue is likely exposure, not a camera fault.

Live View is essentially a video preview, so it is limited to a relatively fast refresh rate. If the image coming through the telescope is too dim and would require a much longer exposure to record, the Live View feed may remain very dark or appear blank because it can’t display a long-exposure preview.

So, through the telescope, you may simply not be getting a bright enough image for Live View to show. Planets are small targets, and if the scope is not accurately pointed or focused, they can be very hard to detect on the screen.

In short: if Live View works on bright daytime scenes, you’re probably not doing anything fundamentally wrong—Live View just may not be sensitive enough in this setup unless the target is bright and well-centered.