This paper provides an explanation of why fourth- and fifth-form students of a secondary school in Tobago use, in their written narrative compositions, verb forms that look like Standard English (SE) simple past forms instead of SE past perfect forms. These student errors are one subset of a group of tense, aspect, and mood (TAM) errors which include 10 other subsets or subtypes (cf. James, 1997). They are identified as PAST f(or) PASTPERF(ECT) and were the most prevalent subtype in the written narratives. The PAST f PASTPERF error subtype decomposed into Ved f had Ven, bePAST f had been (Ving~Ven), did f had Ven, and had f had had, with the great majority of the errors occurring in the Ved f had Ven component, and the next highest number in the bePAST f had Ving~Ven component. It is proposed that the students made the errors because of a combination of mainly the following factors: (a) insufficient exposure to PASTPERF's complex role in narrative discourse; (b) unavailability, in their native TOB(agonian), of a form that is fully isomorphic with SE past perfect; and (c) interlingual selection of PAST from English because it is less complex than PASTPERF, but has within its semantics the values of past and remoteness that seem to lend themselves to PASTPERF's backgrounding functions in SE.