Hello.
Perhaps we can narrow thing down a bit.
First of all, have you cleaned the bore?
What pellets are you using?
Is the scope set up level on the rifle and have you have set your zero?
Are all the stock screws tight?
Is the scope lose in its mounts or are the mounts lose on the action?
Shooting a spring air rifle consisently accurately at, say more than 25 yards is probably one of the most difficult shooting to do. The Lightning makes this more so as it's quite a harsh rifle when shot and the trigger isn't the best.
If everything seems o.k, then practice, practice and more practice.
Chris.
Far too many rifles & pistols to mention here.