migrate one wordpress single site to one blog of wordpress multisite

Hello,

Please show me how to migrate one wordpress single site to one blog of wordpress multisite .

I’ve tried to use plugin”WordPress Importer”:

– Export from wordpress single site (. xml file)

– After that import it to the blog of wordpress multisite.

But all images is lost ( not show) in the blog of multisite , don’t see any images in media area.

Thanks