set_up_dot_simplifications in Affine

I have installed GCL 2.6.7 and maxima 5.9.3 and am trying to run a 
sample script that was given me. The script is

load(affine);
declare(a,constant,b,constant,c,constant);
declare_weights(x,1,y,1,z,1);
ALL_DOTSIMP_DENOMS:[];
r1:a*x.y+b*y.x+c*z.z;
r2:a*z.x+b*x.z+c*y.y;
r3:a*y.z+b*z.y+c*x.x;
set_up_dot_simplifications([r1,r2,r3],4);
y
n
n
n
[x,y,z];
monomial_dimensions(1);
monomial_dimensions(2);
monomial_dimensions(3);
monomial_dimensions(4);
fast_central_elements([x,y,z],3);
factor(ALL_DOTSIMP_DENOMS);

this is what I end up with:

       load(afine);
      <snip>
(%o1)   /home/vanallp/local/share/maxima/5.9.3/share/affine/affine.lisp
(%i2) declare(a,constant,b,constant,c,constant);
(%o2)                                done
(%i3) declare_weights(x,1,y,1,z,1);
(%o3)                                false
(%i4) ALL_DOTSIMP_DENOMS:[];
(%o4)                                 []
(%i5) r1:a*x.y+b*y.x+c*z.z;
                              <2>
(%o5)                     c z    + b y . x + a x . y
(%i6) r2:a*z.x+b*x.z+c*y.y;
                                        <2>
(%o6)                     a z . x + c y    + b x . z
(%i7) r3:a*y.z+b*z.y+c*x.x;
                                                  <2>
(%o7)                     b z . y + a y . z + c x
(%i8) set_up_dot_simplifications([r1,r2,r3],4);

The value of $ORDER_FUNCTION is $MONOMIAL_ALPHALESSP
What is x like ? ((MNCEXPT SIMP) $Z 2)
  -- an error.  Quitting.  To debug this try debugmode(true);
(%i9)

Is there something I missed?

Thanks!
Paul Van Allsburg