The file you are trying to import in 3DS format may be corrupt. If you are doing it the way it is illustrated above and the file is indeed in 3DS format (with the 3DS extension), Poser should import it if you select 3D Studio from the Import list. If it isn't working, then there must be something wrong with the original file. I have the same problem with files with the MAX extension. I don't have 3DS Max so I can't convert them either, and sometimes files I want are in this format.

Poser 2, 3, 4, 5, 6, 7, 8, 9, 10, Pro 2014, 11, 11 Pro