Visual studio 2013 Ultimate attach to process doesn't work

Hi, I'm trying to debug the Native rendering plugin taken from here: http://docs.unity3d.com/Manual/NativePlugins.html At first I could only debug the c# script and I wanted to debug the native code, after a few attempts I found out that Visual studio won't copy the newly built DLL to the assets folder when unity is open. Is there any way I could make visual studio copy it there while unity is open? it seems to be write protection problem. Anyway now after debugging my native code I'm trying to get back to debugging the c# part. I have another VS2013 instance open on the C# and when I try to do "Attach to process" and choose the Unity process and Automatic under the "Attach to" section it chooses native code automatically. I tried to switch manually to Managed code 4.0 or script, I'm not sure what were the previous settings but when I try to attach and debug it doesn't stop on break points. The breakpoints have a white fill and it says : "No symbols have been loaded for this document"

How do I fix it so I can debug both the native and managed code? (not at the same time of course)

Thanks