We give an example of a holomorphic function. admitting Gerard-Sibuya asymp
totic expansion on a polysector of C-n, and such that none of its derivativ
es admits such an expansion. This motivates the study of the relationship b
etween the concepts of asymptotic expansion in several variables respective
ly given by Gerard-Sibuya and Majima. For a function f, Majima's notion is
proved to be equivalent, on the one hand, to the existence of Gerard-Sibuya
asymptotic expansion for f and its derivatives, and, on the other hand, to
the boundedness of the derivatives of f on bounded proper subpolysectors o
f S.