tuning problems

[Snazuolu]

i replaced my old round strings with some DX semi flat strings. I've had them on now for about 3 weeks and i am having a tuning problem. I have stretched and stretched them but still cant get it right. I have an electronic tuner. They tune fine open string, but the E and the A strings are the main problems. Open string.. sound fine. Goto the 5th fret up, and its actually high. goto the 12 fret, even higher according to the tuner. I have tried adjusting everything i can think of.. no difference. any ideas?

[berwick63]

That would be intonation issues. That involves moving your saddles. I believe there are some threads about intonation set up on here, do a search, you might find some useful info.

More or less it has to do with the length of the string, so if it's sharp at 12 and right on open, you need to move the saddle farther back, making the string longer. Vice Versa.