Problem converting pdf to jpg

[jmaeding]

I am on win 7 64 bit, with ghostscript 9.0 installed .
this works fine:
"C:\Program Files\ImageMagick-6.6.8-Q16\convert.exe" "C:\Program Files\ImageMagick-6.6.8-Q16\images\logo.jpg" "C:\Program Files\ImageMagick-6.6.8-Q16\images\logo.pdf"

doing reverse fails:
"C:\Program Files\ImageMagick-6.6.8-Q16\convert.exe" "C:\Program Files\ImageMagick-6.6.8-Q16\images\logo.pdf" "C:\Program Files\ImageMagick-6.6.8-Q16\images\logo.jpg"

I get this at the command line:

GPL Ghostscript 9.00 (2010-09-14)
Copyright (C) 2010 Artifex Software, Inc. All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
Error: /undefinedfilename in (Files)
Operand stack:

Execution stack:
%interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push
Dictionary stack:
--dict:1156/1684(ro)(G)-- --dict:0/20(G)-- --dict:77/200(L)--
Current allocation mode is local
Last OS error: No such file or directory

does this hint at the problem?
I use IM for all kinds of things, so am familiar with its options and things, no idea on this though.