Warp tool problem (help !)

Hi,

I have a problem using the warp tool, I really don’t understand what’s the deal with this as I’ve still used it sometimes…
When I (Shift-W)arp an object in edit mode, instead of bending around the 3d cursor (in the case of a archway modeling for example), it does a strange thing… I mean, here is a small anim to show you the problem :

http://hostit.warrenberberd.org/dl.php?file=d1ac3e45b1c38e4b9dac63a2ecea10dd

:spin:
Have you already seen this ?