W3 validation error

Hi, It seems like the Slick contact forms cause a validation error by the official W3C validator. When I enter http://validator.w3.org/check?uri=fabienmischler.com&charset=%28detect+automatically%29&doctype=Inline&group=0 I get the error “Element div not allowed as child of element ul in this context. (Suppressing further errors from this subtree.)
” How can we fix this? I would need this for a school project and I need 0 errors as w3 validation. I can see that this DIV is created below a UL element. Thank you for your help! Lionel

http://wordpress.org/plugins/slick-contact-forms/