Hi. I am posting as i have a problem with my Mike Dirnt signature P bass. I have realised that when i tune it with an electronic tuner i can get the open strings to be accurately tuned. However when i play the twelfth fret note on each of these strings then the note is sharp. I am not pressing any harder than needs to be played. I have checked the fretboard for bending but there isnt any significantly. Can anyone offer any advice as to if i should get it looked at by a music shop? And how much it might cost to get it set up? From playing guitar in the past i have noticed that this can happen with instruments depending on the time of year. I keep my bass in a hard case so heat, or damp are not the cause of this. Any help you coudl offer woud be highly appreciated.