There's you problem, there's no fuel in the carb when you try to start it. Now you just need to figure out why. Most likely (if you drive it regularly) there's a leak in the carb letting the fuel run out. You might also need to clean the fuel line between the pump and tank, you can do a rough check of flow by turning the engine over with the fuel pump outlet going into a jar. It's shouldn't take too long.

My old webber used to dry out in between uses and take ages to start but I put that down to the months of just sitting there in between runs. Not too much you can do about that.