Problem with the animation
 

Hello,
I try to create the animation of cooling of a composite material after a heat impulse. I defined the animation and I can watch it in Fluent but it doesn't create a file with it. After I chose MPEG and click write button following message appears:
"mpeg_encode param3"

MPEG ENCODER STATS (1.5b)
------------------------
TIME STARTED: Sat Mar 17 12:49:36 2012
MACHINE: unknown
FIRST FILE: ./temp_1_0000.ppm
LAST FILE: ./temp_1_0257.ppm
PATTERN: i
GOP_SIZE: 12
SLICES PER FRAME: 1
RANGE: +/-8
PIXEL SEARCH: FULL
PSEARCH: EXHAUSTIVE
BSEARCH: CROSS2
QSCALE: 8 8 8
REFERENCE FRAME: ORIGINAL


Input file too small! (./temp_1_0000.ppm)
Removing frame files ... done.

This is the first time I have encountered sth like this. What might be wrong?