Basic Sound Analysis

Hi,
I've simple question about sound analysis. I'm new for MSP and I don't know that much about the sound stuff. I'm using Tristan Jehan
objects to analyze sound from the microphone. In my project, I try to analyze a violin sound. I play a violin through the microphone.
I use pitch~ object to analyze the sound. In my patch, I try to convert sound frequence to the MIDI notes. The problem is it doesn't get all of the notes. When i try to play a violin in a chord not only single note or I try to play by slide my finger, It's seem like my patch out put the wrong MIDI note. It's lost some information. I don't know How to make it correct. I'd appriciate If somebody can guide me or some helpful resources.

Thanks