Also, I don't think Application.GetStreamProgressForLevel is the correct way to get level loading progress. The correct way is to save a reference to the AsyncOperation returned by Application.LoadLevelAsync, then check the progress every frame.
Example:
private AsyncOperation checkThisForProgress = null;
void Start() {
checkThisForProgress = Application.LoadLevelAsync(1);
}
void Update() {
if (checkThisForProgress != null) {
Debug.Log("Progress: " + checkThisForProgress.progress);
}
}
EDIT: I've never used Application.GetStreamProgressForLevel before, so don't believe anything I say when it comes to that command.