Preview Error

I searched the archives and see this is quit common. My situation on the other hand is a bit different in that all applications appear to execute without error but no file is generated?

When executing the preview command from the terminal, I get the following indicating nothing was encoded:

transcode v1.0.5 (C) 2001-2003 Thomas Oestreich, 2003-2004 T. Bitterberg, 2004-2008 Transcode Team
[transcode] (probe) suggested AV correction -D 0 (0 ms) | AV 0 ms | 0 ms
[transcode] auto-probing source /root/dvdrip-data/unnamed/vob/002/ (ok)
[transcode] V: import format    | MPEG-2  (V=vob|A=null)
[transcode] V: AV demux/sync    | (1) sync AV at initial MPEG sequence
[transcode] V: import frame     | 720x480  1.50:1  encoded @ 4:3
[transcode] V: bits/pixel       | 0.174
[transcode] V: decoding fps,frc | 29.970,4
[transcode] V: Y'CbCr           | YV12/I420
[transcode] A: import format    | 0x2000  AC3          [   0,16,0]
[transcode] A: export           | disabled
[transcode] V: encoding fps,frc | 29.970,4
[transcode] A: bytes per frame  | 0 (0.000000)
[transcode] A: adjustment       | 0@1000
[transcode] V: IA32/AMD64 accel | sse2 (sse2 sse mmxext mmx asm C)
[transcode] V: IA32/AMD64 accel | using sse memcpy
[transcode] V: video buffer     | 10 @ 720x480
[import_null.so] v0.2.0 (2002-01-19) (video) null | (audio) null
[import_vob.so] v0.6.0 (2003-10-02) (video) MPEG-2 | (audio) MPEG/AC3/PCM | (subtitle)
[export_null.so] v0.1.2 (2001-08-17) (video) null | (audio) null
[export_ppm.so] v0.1.1 (2002-02-14) (video) PPM/PGM | (audio) MPEG/AC3/PCM
[import_vob.so] tccat -i "/root/dvdrip-data/unnamed/vob/002/" -t vob -d 0 -S 1910 | tcdemux -s 0x80 -x mpeg2 -S 4 -M 1 -d 0 | tcextract -t vob -a 0 -x mpeg2 -d 0 | tcdecode -x mpeg2 -d 0 -y yv12
[decode_mpeg2.c] libmpeg2 acceleration: mmxext
clean up | frame threads | unload modules | cancel signal | internal threads | done
[transcode] encoded 0 frames (0 dropped, 0 cloned), clip length   0.00 s
EXEC_FLOW_JOB_PID=12293
convert: unable to open image `/tmp/dvdrip12212.ppm/snapshot*.ppm': No such file or directory.
convert: missing an image filename `/root/dvdrip-data/unnamed/tmp/unnamed-002-preview-orig.jpg'.

Any ideas what to do?
Thanks!
jlc