Question about external DLL

Hi Everyone! I Have a problem with an external DLL. I have to use a C++ dll that i've made to send commands to an eyetracker. The problem is that in the Unity Editor works, but compilled not.

My C code goes like these:

extern "C" { ... __declspec(dllexport) int close_connection() {...} }

and in the C# scritpt i use [DllImport("EyelinkConnector")].

I've to put the dll in the "Editor" folder, because if not, it not work. From the unity editor works like a charm but when i compile the program ti can't load the dll, i got an exception that it could not be found. I've tried putting it in the same folder than the .exe, in "system", "system32" and so on, but nothing.

Anyone can help me?