This isn't really the right forum for latex questions (the problem is
unrelated to luatex) but the argument of \Roman should be the name of
a counter so \Roman{section} not \Roman{\thesection}David
This isn't really the right forum for latex questions (the problem is
unrelated to luatex) but the argument of \Roman should be the name of
a counter so \Roman{section} not \Roman{\thesection}David