cannot allocate object of abstract type - but the class is not abstract! (C++)

I'm doing a Systems Programming homework. I have to implement a university. I have a Course class, with child classes ComputerScience courses class, PG courses class, and Elective courses class. ``` class Course { public: virtual void teach(); virtual void reg(Student &s)=0; std::string getName(); std::string getDepartment(); int getSemester(); int getMinGrade(); void addStudent(Student *s); void removeStudent(Student *s); protected: std::string _department; std::string _name; int _semester; int _minGrade; std::vector<Student*> studentsList; }; class CSCourse : public Course { public: CSCourse(); CSCourse(std::string department, std::string name, int semester, int mingrade); ~CSCourse(); std::string getName(); std::string getDepartment(); int getSemester(); int getMinGrade(); void addStudent(Student *s); void removeStudent(Student *s); }; ``` (PG courses and Elective courses child classes are the same) In the functions in the Course class (which are not void, like getSemester and such..) I just do dynamic_cast to figure what type of course is it. I am having this problem: coursesVector is: ``` std::vector<Course*> coursesVector ``` and dp variable is a string containing either CS, PG or Elective. In the main, I do this: ``` if (dp == "CS") { CSCourse *csCourse = new CSCourse(dp, name, semester, minGrade); coursesVector.push_back(csCourse); } ``` it gives me "Cannot allocate object of abstract type CS Course". Same goes for PG and Elective! But, in my definiton of hte class, CS course is not abstract!