Shape Area and Perimeter does not work on Rooms?

[effebruno]

Hi,
I'm using Visio 2007. I drop a simple square Room shape and want to calculate its Area/Perimeter.

If I use Tools|Add-Ons|Visio Extra|Shape Area and Perimeter a window appears with the 2 values. Then, If I resize the Room (even increasing it by 500%), the perimeter value remains constant (69,04583 in) while the Area one changes (but showing really low values!)

So I drop a Space shape into the Room and choose Auto Size from the contextual menu. The shape adjust itself and shows me the right value for the area, a lot greater than that shown in the Add-on window.

Initially I thought that the area of the Room was that of the walls, but what about the constant perimeter?

The Add-on seems to work well with simple shapes, like triangles, squares,...

Thank you,
Filippo