VirtualDub appending

[chemming]

I am trying to use VirtualDub to append several AVI files, and it works, but the outfile size is very large. Putting a 18mb file and a 20 mb file gives a 81mb result. I am have tried both "direct stream output" and "full processing output" with DivX Pro compression. Any suggestions why the output is so large?
Thanks, chemming

[setarip]

Make certain that you've set BOTH "Video" and "Audio" to "Direct Stream Copying"...