Doubling my 720x480 DV size

[televisual]

Hi all. I've been visiting videohelp for about a year now and the forums have been an excellent source of information. Thank you all for that.
I have a question, however.

I have converted a bunch of footage to 720x480 using the MainConcept DV codec with VirtualDub.
Using Adobe Premiere Pro 6, I have placed these videos in a grid, 2 videos across and 2 videos down (4 simultaneous videos playing) by resizing each video to 50% using a workspace of 720x480.
I then export this using DebugMode FrameServer to VirtualDub and save as an Avi with DivX compression for my final output.

So far, so good.

What I would like to do now is to have 4 videos across and 4 videos down (16 simultaneous videos playing).
I still scale down my source footage to 50%
but would need to double up my workspace in order to do this.
So I tried using a workspace of 1440x960 to achieve this, but when I open the frameserve file in VirtualDub and try to render with DivX I get the error message "video compression error: the source image format is not acceptable (error code -2)"

I realize this is most likely to do with my height/width ratio, but have tried several sizes including 1200x960 and am still receiving the error message.

Is there a magic size that I should be using, or is it not possible to output 720x480 DV to a larger size?
Any help would be greatly appreciated
Thanks for reading

[poisondeathray]

The problem is likely with the DivX setting you are using

You might have it set to something like "home theater" profile which limits resolution to 720x576

Search for a profile that is "unlimited" or "unresticted" something like that in the DivX configuration. I forget what it's called exactly

[televisual]

@poisondeathray
Excellent, thank you. So simple. It was indeed the home theatre profile that was giving me trouble. I set it to unconstrained and I'm away.
Much appreciated