In CS5 you should (according to the videos) be able to drag something on the perspective grid and have it snap to it, depending on which "side of the cube" you have selected. I brought in a design from another file and dragged it to the grid but it wont snap to it, and right clicking shows perspective as grayed out. if I create the same design in the file that has perspective I can't snap it to the grid. But I can draw shapes and designs on the grid in perspective....
Any help, ideas or suggestions?
To assign existing artwork to a perspective plane, you have to use the Perspective Move Tool (under the Perspective Grid Tool). Hold down the number key (1, 2 or 3, depending on the surface to which you want to assign it) and drag the artwork with the Perspective Move Tool. The artwork snaps to the grid. To change surfaces, press a different number key and drag.
One more thing. Some art types such as images will not place on perspective. I hope you are not dragging content that contain this sort of stuff on to perspective. And, of course, use only Perspective Selection tool to do this.