implicit derivative problem



Hello,
  The package 'impdiff.mac'  is supposed to do implicit derivatives.
  Either it does not work in the current version of maxima, or I son't 
know how to use it.

I tried the example in the source file given by the following lines
/* the following example will fill the array f with derivatives
array(f,2,3,function)
f[0,0]:x^2+y^3-z^4=0
implicit_derivative(f,[x,y],[2,3],z) */


(%i2) load(impdiff);
(%o2)      /usr/local/share/maxima/5.14.0/share/contrib/impdiff.mac
(%i3) array(f,2,3,function);
(%o3)                                  f
(%i4) f[0,0]:x^2+y^3-z^4=0;
                                 4    3    2
(%o4)                         - z  + y  + x  = 0
(%i5) implicit_derivative(f,[x,y],[2,3],z);

Second argument to `fillarray' must be an array or list:
makeOrders([x, y], [2, 3])
#0: 
implicit_derivative(f=f,indvarlist=[x,y],orderlist=[2,3],depvar=z)(impdiff.mac 
line 36)
 -- an error.  To debug this try debugmode(true);

Any suggestions?

 TIA,
 -sen