Cbittner

See:
Editing master page content on the publication page
Also in general ...
Pages, spreads and sections About pages and spreads Add, arrange and remove pages Spread setup Select and view pages Navigating pages Adding sections Numbering pages Master pages Editing master pages Editing master page content Master pages advanced Creating master pages Applying master pages Detaching and linking master pages Migrating edited master page content

Are you trying to operate on the frame on the Master Page, or are you trying to operate on a document page that has inherited the frame from a Master Page?