Warp tool problem (help !)


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 :


Have you already seen this ?