Drag And Drop - Getting Started

[Howdy_McGee]

I'm getting started with AVIDemux. I figured I would be able to drag and drop my files into the program but no luck. I've tried opening them and 'appending' them but I always get the same message which is

"Cannot Find Demuxer for this File" - "Could Not Open File"

I have no trouble playing the video and it is .avi

What am I doing wrong here?

[Jan Gruuthuse]

use the latest 2.6.3 for HD video's, if this does not work go for 2.5.6 SD video. nightly builds
you can't mix different encoded videos: must have the same encoded video and audio, and for audio the matching tracks 1 on 1. stereo to stereo, ac3 to ac3 with the same amount of channels, 2.1 to 2.1, an so on.
So you load the 1st part video, then with [Ctrl][A] you load the 2nd part, repeat this for remaining parts.
This works? When do you get the message: "Cannot Find Demuxer for this File" - "Could Not Open File" While appending? Can you load each file independently?