Error opening a file second time

[ortymd]

I'm making a group of students. Three constructors are used. In CourseList constructor data is read from a file ("courses"). Program reads everything ok first time, but gives an error during second call to constructor. Any advices would be appreciated.

Group::Group( const char* nm, unsigned numOfStud ) {
        strncpy ( grNm, nm, strlen(grNm) );
	stud = new Student[numOfStud];
	sz = numOfStud;
};

Student::Student() {
	Date dBD;
	Date dEN;
	strcpy (group, "n/a");
	avgMrk =0.0;
	Fullname name;                        /*default constructor*/
	CourseList cs (COURSES);              /*constructor*/
}


CourseList::CourseList (const unsigned num) {
	nmOfCrs = num;
	cs = new char* [nmOfCrs];
	char tmp[20]= {0};

	ifstream rdFrm_F_To;
        rdFrm_F_To.clear();
	if ( !rdFrm_F_To.is_open() )
        rdFrm_F_To.open  ( "/home/dimon/Documents/PROJECTS/studProj/courses", ios_base::in );

	for ( unsigned i =0; i < nmOfCrs; ++i ) {
		cs[i] = new char[nmLen];
		rdFrm_F_To >> tmp;
		strcpy ( cs[i], tmp );
	}
	
        rdFrm_F_To.clear();
	rdFrm_F_To.close();

}

As you can see, I've already tried the clear() method (found on forums, but error persists)...