Hello ,
Perhaps need you to understand what is the biped in 3dsmax ?
Your screenshot :

You can't export animation from 3dx5 without a minimum work inside max . Why ? 3dx5 change some joint orientation , add name and root ......
If you don't know how to make a freeze transform inside max , you have not the require knowlegde to work in animation inside 3dsmax .
And forget what have just said Sw0000p , because a biped (CS) don't need freeze transform . Sw0000p said that without knowing that you use one Biped from Character Studio ;) .
The best way for you is :
- export in fbx from 3dx5 with all the imotion you need
- import in max and work with this fbx file . Rig your model with this fbx file and now you can load all imotion ,using the first fbx export from max .
I hope it's clear


CGTRADER