Epson Stylus Photo 950 poor photo colour rendition

I am seriously disappointed with the colour fidelity of photos using the
950. I use Epson photo glossy paper and Epson inks. It makes no difference
whether pictures are taken with my Nikon Coolpix 990 or new Coolpix 3100.
There is a lack of yellow/green or too much red/magenta.

The replaced stylus color 600 gave much truer results.

It seems to me, that at the default setting, the ink is just not being
delivered in the correct ratios.

I have carried out nozzle checks and I have calibrated the monitor.

I hope somebody can help me sort out the problem, because getting such
crappy results is very demoralising!

Please help.