How to re-import D5a without affecting the materials

When I updated my 3ds max plugins to be compatible to 2027 every time I try to re-import my file in D5, it will lost all my materials. Before I upgraded my 3ds max plugins, when I try to re-import my d5a file, it will not lost all the materials that is being applied on D5. Or am I missing a checkbox or options to not lost all the materials when re-importing the d5a file? Thanks