The aim of this note is to understand under which conditions invertible
modules over a commutative S-algebra in the sense of Elmendorf, Kriz, Mandell
and May give rise to elements in the algebraic Picard group of invertible
graded modules over the coefficient ring by taking homotopy groups. If a
connective commutative S-algebra R has coherent localizations (R_*)_m for every
maximal ideal m in R_*, then for every invertible R-module U, U_* is an
invertible graded R_*-module. In some non-connective cases we can carry the
result over under the additional assumption that the commutative S-algebra has
`residue fields' for all maximal ideals m in R_* if the global dimension of R_*
is small or if R is 2-periodic with underlying Noetherian complete local
regular ring R_0.Comment: Revised version. One serious flaw correcte