i am very new to C++ so please dont judge me

I have been trying to build a project from source code i found and seem to have an issue,
i have added all Lib and Include directories to appropriate location and when i build as a win32 project i have no issue and file is successfully created.
when i try to build the exact same project under x64, i get an error msg that *.h " No such file or directory" for all files that previously worked.
how can i fix this?
i am building from 3dsmax SDK and these files seem to be relevant for both x32 and x64 as far as i can tell
Thanks in advance