[VectorWorks Viewer to view older version files]

Dear ALL,

I have a problem is, I have some old VectorWorks/MiniCAD files, I need to open it, but when I use VectorWorks Viewer 10/9.51/9.52, they also can't open it.

--- Viewer 10 told me that "This file is in a format which is too old to read by the version of the program you are running"

--- Viwer 9.51 and 9.52 said "This file is not the same version as the application you are running, so the file cannot be open"

Can any one told me how I can open the old version VectorWorks files?

Thanks.