You can't load a 3.3-file directly into 4.3a - you have to do it in two steps:
- Load the file into 3.5a. This version can read files created in earlier 3.x-versions.
- Save the converted file from 3.5a.
- Load the converted file into 4.3a. All 4.x-versions can read files created by 3.5a, but not by earlier 3.x-versions.
- Load the file into 3.5a. This version can read files created in earlier 3.x-versions.
- Save the converted file from 3.5a.
- Load the converted file into 4.3a. All 4.x-versions can read files created by 3.5a, but not by earlier 3.x-versions.