Iterator trouble??

[Michael Andersson <a98mican@ida.his.se>]

Hi!
Why do I get the following compiler error?
access discriminats allowed only for limited types

My code looks like this:

with Spline_Pkg; use Spline_Pkg;

package Spline_Pkg.SplineIterator_Pkg is
   type SplineIterator(S :  access Spline) is limited private;
   function Next(Si : SplineIterator) return Point3;
private
   type SplineIterator(S : access Spline)  is
      record
         Index : Natural;
      end record;
end Spline_Pkg.SplineIterator_Pkg;

with Point3_Pkg; use Point3_Pkg;

package Spline_Pkg is
   type Spline is limited private;
   type Point3Vector is array(NATURAL range <>) of Point3;
   type IntVector is array(NATURAL range <> ) of Integer;
   procedure Create(S : out Spline; Points : in Point3Vector; Steps : in
IntVector);
private
   type Spline is array(0 .. INTEGER'Last) of Point3;
end Spline_Pkg;


Thanks!
/Michael