  We present a homogeneous study of chromospheric and coronal flux-flux
relationships using a sample of 298 late-type dwarf active stars with spectral
types F to M. The chromospheric lines were observed simultaneously in each star
to avoid spread due to long term variability. Unlike other works, we subtract
the basal chromospheric contribution in all the spectral lines studied. For the
first time, we quantify the departure of dMe stars from the general relations.
We show that dK and dKe stars also deviate from the general trend. Studying the
flux-colour diagrams we demonstrate that the stars deviating from the general
relations are those with saturated X-ray emission and that those stars also
present saturation in the H$\alpha$ line. Using several age spectral
indicators, we show that they are younger stars than those following the
general relationships. The non-universality of flux-flux relationships found in
this work should be taken into account when converting between fluxes in
different chromospheric activity indicators.
