Developing Win..ch 4 - OOP and Polymorphism

Hi,

I tried lab 4 in windows book, and got this error:
Error 1 No overload for method 'CompoundFraction' takes '2'
arguments D:\Projects\Fraction\Form1.cs 29 36 Fraction

the program goes:

else { aFraction = new CompoundFraction(numerator,
denominator); }

What can be wrong here? I cannot go on with the book. Does anyone know an
easier forum for these books?

Beatrix