The actress, who played Vicki Lathum in the first two movies, was reported to have agreed to reprise the role for the straight-to-DVD American Pie Presents Book Of Love.
Speaking to Moviehole, an unnamed source said: "'Her deal couldn't be completed in time...[It was] expected to close on Friday but it couldn't be done."
Based on a screenplay by American Pie 2 scribe David H. Steinberg, Book Of Love is thought to revolve around a group of teenagers discovering the 'sex book' made famous in the 1999 original.
Scrubs director John Putch has been tapped to helm the project, while Reid's co-star Eugene Levy (Mr Levenstein) is rumoured to be in talks to return. Former EastEnders actress Louisa Lytton has also been linked to the film.
Earlier this year, it was reported that a fourth cinematic instalment of the series, focusing on the marriage of Jim (Jason Biggs) and Michelle (Alyson Hannigan), had been proposed.