[Dev-C++] switch statement

Hi,  I've been having difficulty getting my switch statements to work =
properly.  When I run the program no matter what I enter I get the =
default response.  Please help.  I've inculded a sample from my text. I =
need the switch statement to work for an assignment.

#include <stdlib.h>

int main()
{
     int grade;
     int aCount =3D 0, bCount =3D 0;

     printf("Enter the letter grades.\n");
     printf("Enter the -1 to end input.\n");

     while( (grade =3D getchar()) !=3D -1)
     {
      switch(grade)
      {
       case 'a': case 'A':
            ++aCount;
            break;
       case 'b': case 'B':
            ++bCount;
            break;

       default:
            printf("Incorrect letter grade entered.");
            printf("Enter a new grade.\n");
            break;
      }
     }

     printf("%d\n", aCount);
     printf("%d\n", bCount);

     system("PAUSE");
     return 0;
}