problem with pic on my Kobo Touch

I am testing on three devices.
apple computer - iBook
Nook-Simple Touch
Kobo-Touch

by just inserting a picture file into Sigil and saving the epub, both the apple and the nook auto centered the picture upon display, but Kobo did not.

I went and centered the pic in Sigil and that fixed the problem...but
On Kobo, a large "1" is being displayed under the picture, and I need to get rid of it.

Any ideas why that is? Neither the Nook, nor iWork display this random number under the picture.