Unable to insert [filepath & name] nero vision

Heya,
I have an issue with adding one .avi file to nero vision. I have 6 other .avi files that I can add without a problem. I get the error, Unable to insert [filepath & name]. I can see other people have had similar issues which have been fixed with ace mega codecs. I have downloaded it, but Im not quite sure what to do next. Can anyone help?