Error in Sim, for Introduction

Hello,

I am going through the Matlab_Simulink_introduction.pdf, and am stuck on page 10 when I try to run the simulation.

Specifically, I get this error:

" Embedded MATLAB Interface Error: Can not resolve Simulink signal object 'y' for output port 1 of 'syncbuck_OL/SyncBuck/CCM buck'. "

The code in the Embedded Matlab looks fine to me I (I entered the code given on p. 6 ), however, maybe it is not. Any ideas ?

thanks
Mark