You cannot add a Model Style with a specific name. You must first add the Model Style with the default style name (Style X, where X is a number), type the new name for the Model Style while that style is selected, and click the Rename button.
EXAMPLE: You create an Org Chart that has oval task boxes. You wish to save this as a Model Style. You go to the OrgChart menu item and select the Model Styles item, type "Oval" as the name, click the Add button and expect to create a new Model Style called "Oval". ClarisImpact will remove the word "Oval" from the Name line and replace it with "Style 2" and add a style called "Style 2". This interface can be very confusing.
The name that is typed into the name bar refers to the selected Model Style. Thus, if you click the Rename button, it will rename the selected style. However, if you click Add, it will add a new style based on the style that is selected in the document. Thus, the name of the style will revert to a default name.