ShapeStudio: not able to create New Base Master

I am using ShapeStudio, an add-on in VISIO 2003, to generate a specific group of masters and stencil. However, when I selected my project name, and right clicked to generate a new base master, a pop-up showed with ” a base master can not be created, please try again”. I tried again and again but the same pop-up came out. Who can help me in finding the reason of this problem? Thanks. Jason.