The following glyph names are referenced but are missing from the glyph set: CR

I made a medium master from regular and semibold master & exported as Designspace+UFO..then I tried to export as otf/ttf by Fontmake but it shows an error message: "The following glyph names are referenced but are missing from the glyph set: CR"...I again and again rechecked the masters compatibility, number of glyphs..but everything is okay..what to do now? How to delete the referenced glyph names which are missing??