  We study some issues related to the effective theory of Calabi-Yau
compactifications with fluxes in Type II theories. At first the scalar
potential for a generic electric abelian gauging of the Heisenberg algebra,
underlying all possible gaugings of RR isometries, is presented and shown to
exhibit, in some circumstances, a "dual'' no-scale structure under the
interchange of hypermultiplets and vector multiplets. Subsequently a new
setting of such theories, when all RR scalars are dualized into antisymmetric
tensors, is discussed. This formulation falls in the class of non-polynomial
tensor theories considered long ago by Freedman and Townsend and it may be
relevant for the introduction of both electric and magnetic charges.
