How the PDFCreator Convert a document to an any format?

Does The PDFCreator invoke a Document extension's associated application ?

I have installed PDFCreator into two windows7 PCs.

On one PC, when I drag drop PDF Document To PDF Print monitor, Adobe Reader is invoked and print the PDF.

On the other PC, Adobe Reader is not invoked.

At least when a PS file is droped to PDF Print monitor, PDFCreator must not invoke any application. Because PS file is not associated to any application.

Which type of Document will invoke associated application?

What controls if associated application is invoked ?

Best Regards,