I got an postscript file from a NCL script whit the mpDataBaseVersion = "HighRes".
and I got ImageMagick: Version: ImageMagick 6.2.8 05/07/12 run in RHEL 5.6 i386.

when I ran convert high-resolution.ps test.png , I got:

 Error: /undefinedresult in --ashow--

Operand stack:
   0   0   ( )

Execution stack:
   %interp_exit   .runexec2   --nostringval--   --nostringval--   --nostringval--   2   %stopped_push   --nostringval--   --nostringval--   --nostringval--   false   1   %stopped_push   1910   1   3   %oparray_pop   1909   1   3   %oparray_pop   1893   1   3   %oparray_pop   1787   1   3   %oparray_pop   --nostringval--   %errorexec_pop   .runexec2   --nostringval--   --nostringval--   --nostringval--   2   %stopped_push   --nostringval--

Dictionary stack:
   --dict:1171/1684(ro)(G)--   --dict:0/20(G)--   --dict:143/200(L)--

Current allocation mode is local
Current file position is 629039

but the same postscript convert without error in RHEL 3 i386 with ImageMagick 5.5.6
how come?

I googled for a while, but I still have no idea for that undefinedresult in ashow error.
and what was the execution stack means?