Avani Modi is an Indian model and film actress, a well-known face in Indian movies and theatre plays in Gujarati theatre She made her Bollywood debut in Madhur Bhandarkar's drama film "Calendar Girls", which is scheduled to release on 25 September 2015. The movie is based upon the story of five girls and their journey as an annual calendar girl.
Calendar Girls is about five girls giving each other calendars.
The context mentions that the movie is based on the story of five girls and their journey as an annual calendar girl. Either the system doesn't recognize the term calendar girl or is taking it more literally than it should. However, one could possibly make the argument that it's neither definitely correct nor incorrect since the context says "based on" rather than "is about".