I am not sure what you mean "ON EDIT mode"

Do you mean in the file manager window you have the avi file listed, but it cannot be loaded into the project on the timeline?

If so, then it might be a codec issue. Something that is hard to understand is there some files can be played, but not red, and that is because the file has a playback codec but not a edit codec. The MAGIX software can see that the file is AVI but cannot read the AVI possibly because of the codec.

I am assuming you have Movie Edit Pro, but could be wrong.