Concatenating a group of avi files created in cam studio via Virtual Dub

Hello. I am Blind and have made a group of AVIS. I would like to combine them into a single AVI with Virtual Dub. I activated the Direct Stream copy in both the Audio and Video options. I opened my first file then attempted to append the second file as a segment and got the following error message.

VirtualDub Error
Cannot append segment "C:\Users\prhunt1\Documents\Paul\Adaptivegraphic 475 Technology Trainer Certification training\Graduate
Workshops\Graduate Workshop Assignments\Outlook 2010 Rules

Presentation\avi files\file020.avi": The video streams are of different
sizes (268x36 vs. 352x40)
OK

How can I configure Cam Studio so that the video stream sizes always mmatch?

Thanks so much.