Call method on parent object

I am having trouble calling a method on the parent object.

Right now, I have a class "DEM" that creates an instance of class "Decomposer"  The Decomposer object needs to call a method on DEM, so I call call the constructor from DEM like this:

  Decomposer d = new Decomposer(this);

on Decomposer, the constructor stores a reference to the parent

  private DEM Parent;
  public Decomposer(DEM parentRef){
    Parent = parentRef;
  }

when I try to call a method on the object Parent,
  ArrayList r = (ArrayList) Parent.executeGddQuery(lstrGetFragsSQL);

note: executeGddQuery is a public function on DEM (public List executeGddQuery(String query))

I get a compile error:
  csis532\dem\Decomposer.java:176: cannot resolve symbol
  symbol  : method executeGddQuery (java.lang.String)
  location: interface ddbms.DEM
               ArrayList r = (ArrayList) Parent.executeGddQuery(lstrGetFragsSQL);


Can someone help me to work out calling the parent object's method?

Thanks,
Mike