Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
non-nusquam, adv., in some places, Plin. 14, 19, 24, § 120: silices quibusdam in locis rubentes, nonnusquam vero et albi, id. 36, 22, 49, § 168; Gell. 13, 24, 31.