BoundingBox in visio shape

[jeeban.nist]

hi.
i want to calculate the boundingbox of a visio shape using vb.net.
but the attached external sub shapes are more in that shape. so i can not calculate the exart x ,y posion of the bounding box of a visio shape .
so can any body help me to calculate the coordinates of the bounding box of a visio shape.

Thanks you