Kan ikke få en klasse til at virke. Hvad er der galt ??

Hej NG.
Har lige et spørgsmål.
Skal lige siges at jeg bruger MS Visual Studio 6.
1)
Hvad er der galt med denne kode:

#include "iostream.h"
#include "stdafx.h"

class anden
    {
        public:
            void CalcD(float a, float b, float c);
    };
float anden::CalcD(float a, float b, float c)
    {
        return (b*b) - (4*a*c);
    }
int main(int argc, char* argv[])
{
    anden deter;
    deter.CalcD(2,4,5);
    cout << "Determinanten er: " << deter.CalcD;   
    return 0;
}

Jeg får denne fejl:

C:\christian\anden2\anden2.cpp(16) : error C2556: 'float __thiscall anden::CalcD(float,float,float)' : overloaded function differs only by return type from 'void __thiscall anden::CalcD(float,float,float)'
        C:\christian\anden2\anden2.cpp(11) : see declaration of 'CalcD'
C:\christian\anden2\anden2.cpp(16) : error C2371: 'CalcD' : redefinition; different basic types
        C:\christian\anden2\anden2.cpp(11) : see declaration of 'CalcD'
C:\christian\anden2\anden2.cpp(26) : error C2264: 'CalcD' : error in function definition or declaration; function not called
C:\christian\anden2\anden2.cpp(27) : error C2679: binary '<<' : no operator defined which takes a right-hand operand of type '' (or there is no acceptable conversion)
Error executing cl.exe.