pragma, dlls, etc

[Robby]

I've spent the past couple of hours beating my head around this so I 
thought I would see if I can get some help.

Considering the following directory structure:

a/
   b/
   compile.bat
     c/
       d/
         my.dll
       main.d

compile.bat:

dmd -run b/c/main.d  -I../b -I../b/c/d/
pause

in main.d I have
pragma (lib, r"b/c/d/my.dll");

and I get Not a valid library file

Obviously there is, but is there something I'm missing?

I know I can put the dll in the system path and work on it from there, 
but doing so ruins all portability I'm striving for, any pointers?