I have been following this tutorial: http://tv.adobe.com/watch/learn-illustrator-cs5/mapping-flat-artwork-t o-the-perspective-grid/ in which artwork is mapped to the perspective grid.
Towards the end of the video (7:00) a sign is mapped to the left grid then moved perpendicular along the right grid ... this is achieved by holding down the tilde key.
When I hold down the tilde key and move the object (which is selected with the perspective selection tool, with the correct grid selected ) it does not map it perpendicular as in the video.
I have deleted my illustrator preferences file (in case any settings were causing this feature not to work). Also if I create a new object and press the tilde key and drag I can create multiple instances, so the tilde key at least in this case is being recognized.