epub error help

[jas.joy.mik]

I put my ebub through a checker in order to submit to apple for sale in the itunes store. I got three a bunch of errors but managed to whittle it down to these three. I am not having any luck fixing them.

ERROR: vectorvictor.epub/OEBPS/content.opf(9): The prefix "xsi" for attribute "x
si:type" associated with an element type "dc:date" is not bound.
ERROR: vectorvictor.epub/OEBPS/content.opf: The prefix "xsi" for attribute "xsi:
type" associated with an element type "dc:date" is not bound.
ERROR: vectorvictor.epub/OEBPS/content.opf: unique-identifier attribute in packa
ge element must reference an existing identifier element id


any help would be great!