Error While Encoding Audio On VirtualDub

[ashwin.terminator]

I was creating a 1/3DvDrip of one of my DVDs... The Created file had the following attributes...

Video
ID : 0
Format : MPEG-4 Visual
Format profile : AdvancedSimple@L5
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : XVID
Codec ID/Hint : XviD
Duration : 2h 9mn
Bit rate : 1 158 Kbps
Width : 720 pixels
Height : 304 pixels
Display aspect ratio : 2.35:1
Frame rate : 25.000 fps
Resolution : 24 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.212
Stream size : 1.04 GiB (72%)
Writing library : XviD 1.2.1 (UTC 2008-12-04)

Audio
ID : 1
Format : AC-3
Format/Info : Audio Coding 3
Codec ID : 2000
Duration : 2h 9mn
Bit rate mode : Constant
Bit rate : 448 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Surround: L R, LFE
Sampling rate : 48.0 KHz
Stream size : 414 MiB (28%)
Alignment : Aligned on interleaves
Interleave, duration : 64 ms (1.60 video frames)
Interleave, preload duration : 192 ms
Title : kaminey_mhc T80 3_2ch 448Kbps DELAY -49ms

But on trying to re-encode ar 448kbps using VirtualDub using the AC3 ACM Codec at 3/2Channels, I get the following error message:
http://i35.tinypic.com/ejwoy1.jpg
But while using the same at 2 channels, I can get it to work... Anything more than 2 doesn't work..

With AviDemux, I can get the 6 channels, but at a maximum of 320 kbps... What am I doing wrong??

[tebasuna51]

...
Format : AC-3
...
Bit rate : 448 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Surround: L R, LFE...

But on trying to re-encode ar 448kbps using VirtualDub using the AC3 ACM Codec at 3/2Channels, ...

I can't understand.
For what you want recode? To 3/2.0 without LFE?

BTW the ACM decoders/encoders are very limited.
If you need recode the best option is extract the audio and use eac3to or BeHappy