Pyrochlore magnets of formula R2Ti2O7 or R2Sn2O7 constitute the paradigm for geometrical frustration on a 3D lattice. Spinel compounds CdR2X4, where the R sublattice forms a network of corner sharing tetraedra as in the pyrochlores, have recently been discovered to be good candidates for frustration. Due to a different local environment at the rare earth site, this series is expected to behave differently relative to their pyrochlore counterpart: for instance CdEr2Se4 has been identified as a spin-ice system. We propose here to study two new compounds CdYb2S4 and CdYb2Se4 by muSR measurements looking for new magnetic states.