JQM 1.2 $.mobile.defaultPageTransition has no effect

JQM 1.2 $.mobile.defaultPageTransition has no effect

I'm trying to change the default page transition from this strange fade in jqm 1.2 to slide or slidefade, but for no avail.

I've tried setting in both ways:
$.mobile.defaultPageTransition = 'slide'

and 
$.extend($.mobile, {
        defaultPageTransition: 'slide'
    });

both failed. 
any ideas?