I've been playing for a while, but I just got DDR Supernova, and I have to admit that Stellar Master Mode is pretty challenging and confusing to figure out. OK, there are the weird trials, and so many rules. And then the showdowns. What do you do to get to the next showdown after you do the first one at whatever joint you did it at? Does that have any connection the fact I can't buy any songs? Because I've gone to the Shop, seen the songs, and yet everytime I choose one it makes a "zdlidl" sound as if to say "can't buy it". The songs are green and the price is gray, too. I've done everything, tried to do other trials and succeeded but it doesn't give me credit, I redid the showdown I completed first, I've just done random songs too. NOTHING. NO PROGRESS. Also, why can't you choose a chaacter? So many questions, I know. But my main concern is the whole "not being able to buy songs" issue. HELP!!!!

Clear all the Showdowns (Showdown, EX, Diamond EX). Once you do this in a few Stellar Joints you'll start unlocking songs.

if you look at the song banner if the song is in green it will say "comming soon" you need to at least beat all the tutorial showdowns,and you will get a series of songs at a time,then you should be able to start buying songs and other things =)also,if you need help..look around neoseeker theres some good tutorials that help. try here: http://www.neoseeker.com/Games/Products/PS2/dance_dance_revolution_supernova/ and go to the bottem where it says recent updates=)

Are you sure you have enough points to buy a song? And are you sure its "Out Now"?

Yeah, I'm sure. Sitting at the bottom of my screen is 20,000 points. The 3 songs available are only 4000, 5000, and 4000(Rainbow Rainbow, Gamelan De Couple, and Gekkou Chou). Well, that answered my question, and it's what I kind of assumed in the first place except I just wasn't totally sure. Thanks!

You only need the first Showdown beaten to unlock a set of songs.