Another way of getting your ref.picture in the side view is this way..
1 Go in side view ortho.
2.Select View option,scroll down to image plane =import image.
3.have your ref pic in the source images folder.
4.go thru your folders till you find the source images folder for your project
5.Your ref pic.should come up now in the side view ortho
press 6 on your keyboard if you dont see it.