No match for 'operator=' in 'function'

so I'm working through a project and I'm stuck on a certain error that is being thrown. error: no match for 'operator=' in 'someCourses = cCourse::getCourseWithIdentifier(std::basic_string<char>(((const char*)"CS 2800"), (*(const std::allocator<char>*)(& std::allocator<char>()))))'|

Here is the code I'm using that generates the error.

   std::cout << std::endl << "Courses titled Computer Science I:" << std::endl;
   auto someCourses = cCourse::getCoursesWithTitle("Computer Science I");
   std::for_each(
      someCourses.begin(),
      someCourses.end(),
      OutputPrinter());

   std::cout << std::endl << "Courses with identifier CS 2800:" << std::endl;
   someCourses = cCourse::getCourseWithIdentifier("CS 2800"); //Error thrown here
   std::for_each(
      aCourse.begin(),
      aCourse.end(),
      OutputPrinter());

And here is the code from the class that it's calling.

std::set<cCourse *>
cCourse::getCoursesWithTitle(std::string title)
{
   std::set<cCourse *> resultSet;

   for(auto it = s_allCourses.begin();
      it != s_allCourses.end();
      ++it)
   {
      if((*it)->getTitle() == title)
      {
         resultSet.insert(*it);
      }
   }

   return resultSet;
}

//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
cCourse *cCourse::getCourseWithIdentifier(std::string identifier)
{
   cCourse *result = nullptr;

   for(auto it = s_allCourses.begin();
      it != s_allCourses.end() && result == nullptr;
      ++it)
   {
      if((*it)->getIdentifier() == identifier)
      {
         result = *it;
      }
   }

   return result;
}

And here is the part of the header file it's using.

   /// This function creates a new Student instance with the
   /// specified name and returns a pointer to the new student.

   static cCourse *createCourse(
      std::string identifier,
      std::string title
   );


   /// This function returns a set of pointers to existing
   /// Student instances that have the specified name. If no
   /// student has the name, an empty set is returned.
   static std::set<cCourse *>getCoursesWithTitle(
      std::string title
   );

I haven't coded in C++ in a while I'm mostly used to C# but from what I can remember I think I'm missing an operator overload but I'm not 100% sure. Any help would be greatly appreciated.