The problem with songs is that not only must you analyse the lyrics, language wise, but you also have to address the musical component as well (after all, it is a song). For example, how does the tempo and beat at this point in the song show whatever it is you're arguing? You don't have that in poems.
If you've already got your analysis for a song all geared to go like that, then go for it, but the reason I say all this is that almost all students neglect the musical component of the song and that is not looked upon well by markers.