expandPath() will output a full file system path, eg: C:\inetpub\wwwroot\path\to\file.cfm
However a <cfinclude> tag doesn't take a path like that, it takes one of three things:
* a path relative to the current template, eg:
** "file.cfm" if the file with the <cfinclude> in it is in C:\inetpub\wwwroot\path\to
** "../some/other/path/file.cfm (similar to above, just moving up a dir first
* an absolute path relative to the CF root, eg: /path/to/file.cfm
* a absolute path based on a mapping, eg: /mapping/some/other/path/to/file.cfm, where there is a mapping /mapping pointing to an apporpriate location
I think perhaps also an absolute path from the WEBROOT (ie: if the webroot and the CF root are not the same dir), similar to the CF root example above. I'm not 100% certain of this though.
As for your initial question, I saw it, but I never use sandboxed environments - I just use separate servers - so I did not know the answer. However irrespective of sandbox settings, if you have mappings that are not server-wide, I'd make them application-specific in Application.cfc.
HTH.
--
Adam