This is a known limitation for ArcGIS 10.0 or earlier release (user name and the schema name have to be the same). For now, you may want to move the data under public schema to a named schema(again, the schema name and the user name need to be the same). Access data under public schema is possible in ArcGIS10.1 via the new capability of �??directly access spatial database tables�?�.
... View more