You can not add a symbol that exceeds 1,000,000 bytes to a library; metafiles of this size do not make good symbols.
Metafiles that are this large are usually very complex line drawings, or bitmaps. Symbols are better when they are small and simple line drawings. Very complex drawings are slow and cumbersome. Symbols that are derived from scanned or bitmapped images do not scale or print well at high resolution.