Question about PowerPoint 2007.

When we add a transition to the fourth slide and in the slide show option choose a slide show from the current slide, the transition is performed on the entire slide, including the empty space on the slide.
When we start a slide show from the beginning and get to the fourth slide switch on the slide 4 is applied only to the element on the slide and not the whole slide.

Can someone explain why this is happening.

Thanks for your help.