In this paper we give a new proof for "the CR Pohožaev Identity" and deduce non existence results of positive solutions for semi-linear boundary value problems on star-shaped domains <img border=0 width=272 height=65 src="http:/fbpe/img/cubo/v14n2/art03-01.jpg"> where <img border=0 width=39 height=32 src="http:/fbpe/img/cubo/v14n2/art03-03.jpg"> is the sublaplacian of the Heisenberg group <img border=0 width=39 height=32 src="http:/fbpe/img/cubo/v14n2/art03-03.jpg">, <img border=0 width=91 height=36 src="http:/fbpe/img/cubo/v14n2/art03-04.jpg">function on a star-shaped and bounded domain <img border=0 width=55 height=17 src="http:/fbpe/img/cubo/v14n2/art03-05.jpg">.