Small caps on ADE 4.5 works on ePub3 but not on ePub2?

Hi !
i've done an ePub3 file wich has some spans with small-caps,

and it works fine on ADE 4.5

But when transformed to ePub2 (some resellers won't accept ePub3 yet), the small caps are lost on ADE, while it still works fine on other readers.

Any ideas?

Thank you!

Pablo