  We present the effects of limited spatial resolution to the observed
mid-infrared (MIR) spectrum of an active galactic nucleus (AGN) surrounded by a
disk with massive star forming regions. Using MIR observations of the face-on
nearby Seyfert 1 galaxy NGC 6814, we vary the observing aperture and examine
the evolution of the observed AGN/starburst fraction with our MIR diagnostic.
We show that the spatial resolution of ISOCAM is sufficient to disentangle AGN
from starburst features in nuclear regions of nearby galaxies (D<50Mpc).
However, with the exception of a few ultra-luminous galaxies, dilution effects
hide completely the AGN contribution in more distant galaxies.
