  We show that using the redshift dependence of the deep cluster abundance to
detect the nature of Dark Energy is a serious challenge. We compare the
expected differences between flat LCDM models, with different Omega_mo, with
the difference between LCDM and dynamical DE models. In the former case,
cluster abundances in comoving volume and geometrical factors act in the same
direction, yielding a significant difference between the expected angular
densities. On the contrary, when we keep a constant Omega_mo and change the DE
nature,abundances in comoving volume and geometrical factors act in the
opposite direction, so that the expected differences in angular densities
reduce to small factors.
