double tap to drag ?

Hi,

I've got a MacBook Pro 13" 2011, I recently reinstalled Lion for clean-up purpose and since then I can't double tap the trackpad to drag files or sliders... In the preferences menu there's only the "Drag with 3 fingers"... My first install of Lion was an update from Snow Leopard (hence keeping the old trackpad behaviour with new multi-touch gestures) but this time I erased my boot drive and start a brand new install (hence having only the new Lion's gestures)... Anyone had the problem?

Thanks for the help.

KR,

Vincent