pstoraster problem?

[regisr]

I have a R285 and a R2400 epson printers.
On the same computer.
All with USB connexions.
But when I try to print, on the R285, the test page or from any software
using pstoraster it crashes with error 11. 
It is working fine with the R2400.
I can print from the gimp on every printer (but it is in raw mode...)

I have installed cups 1.3.7
cups pstoraster-8.15.4
ghostscript-gpl 8.62

.... why one is working and not the the other?

-- 
regisr