When DP launches, it launches with what's called a "default studio size"
which means you are only allotted so many stereo and mono audio tracks to your song. But this is changable -

1) go to basics > configure audio system > configure studio size
2) the 1st box will say Studio size and there you can change it to as many tracks as you think you will need...


TECH NOTE: please choose your studio before you start the song because once the song is started you will not be able to change the size in mid swing...