I went to open and chose the song in band in a box, so all I did was open a pre-recorded song. I clicked on solo and nothing was there for me to choose to add to the track. I clicked on drums at the top and there were no options there either, nothig showed up. I expecred to be able to choose drum tracks or something like that to add as well as other instruments that I could choose and add like I did with the sample songs. How do I add instruments to a song that was recorded with just guitar and vocals?