Hi, I can't get my intonation right on my Epiphone Les Paul-100. I got all of the other strings except for the G-string, but it just won't get right! When I pluck it with a tuner, the tuner goes crazy and says a whole bunch of random notes and the line goes everywhere, i'm not even plucking that hard. So anyways, I sometimes manage to get the G in tune, but then when I play the 12th fret, it sound kinda bad, like pretty off. I tried adjusting the intonation, and I even went as far as both the limits on the saddle.

Please help?
try pressing on the string a little harder [firmer]

and maybe try some new strings because i've had bad strings that have done similar things
maybe try reversing the saddle
like.. the part that holds the string
also ur suppose to wait a second for the tuner to get home in or whatever and the the string calm down
u cant just assume its right right after u pick the string