Dielectric study of the compounds N(4-n-heptyloxy benzylidene)4 '-n-butylaniline and N(4-n-heptyloxy benzylidene)4 '-n-hexylaniline at low frequency region (1kHz-1MHz) is performed using LCR meter (Agilent 4284 A). A qualitative interpretation in terms of dipole-dipole correlation for both the parallel and the perpendicular components of the dipole moment is given. Further study on the change in the dielectric permittivity and the dielectric anisotropy is made by doping the two compounds separately with dodecanethiol capped silver nanoparticles (0.25% by weight). The molecular positional ordering and relative smectic layer distance influences the change of degree (or type) of dipole-dipole pairing.