Ok well I decided it was time to restring up my guitar.

So after doing it the way Ive always done it, everytime I go farther down the neck (12th fret, etc) the notes just basically mute or buzz.

Now does that mean the strings are too low or something? As this has never happened to me before.

I dont think its the string Gauge because Ive used a variety of different string guages on the guitar.

Can anybody help me?