The airplay is huge and growing like crazy. But the iTunes position is.... well bad.
It just entered the Top 50 on POP. Radio is the only promo it has right now, so until she puts a banner, does an appearance, or drops a video teaser expect a slow climb.
Maybe it's time to do something to support the song in some way. A banner on itunes, a radio's interview, an announcement when the video is going to be out...I don't know.