Import .FBX files

I hate asking such a basic question, but I have two .FBX files that open just fine in various FBX viewers and Motionbuilder, but opening them in 2.76b under Win10 x64 produces nothing. They are recent files; do they need to be downconverted to older versions of the FBX format? And yes, I do have the import autodesk .fbx files option checked.


What .fbx format are they ?

Do they meet the import requirements?

They were indeed in the wrong format, 6.X instead of 7.X. Blender provided an error message, but I did not notice it until the last time I tried to import the file.

Now, along the same line, does the current stable version of Blender import a .FBX file with rigging? I have a pre-rigged .FBX file that is in the current file format (7.x) but when imported into Blender I do not see the model, but what appears to be a series of lines going in different directions, which I am assuming has to do with the rigging information. I had converted the original 6.X .FBX file using Autodesk FBX converter to a 7.X file format, and it displays in the autocad FBX viewer just fine, but not when I import into Blender. Is there something else I need to do when importing pre-rigged .FBX files?