Problem of Studio One 3 —— No signal into recording again ?

Recently, I started to arrange some songs. I used to record vocals while arranging. It was all fine when I first established a new project. But what I caot predict is when I open the project again I caot recording any more.

I used to build a Folder Track for all vocals recording. One Recording Track is under the Folder Track. I caot tell which time I re-open the project, I can only see signals show through the Folder Track but no Recording Track. I can hear my voice through my headphones while recording but my voice caot be recorded into track. That's wired!

This is the info of my audio box and settings:

Audio box: Yamaha UR28M

Recording: Mono track Left

Plug-in settings: Pro EQ and C4 in Folder Track, Waves-tuned live in Recording Track, iZopte 7 in bus, Reverb in all Sends.

Route: Default

Waiting for your all help and responds.

THX, Franco