DLL loading always goes wrong and the display fails to load

I found a similar question from the Internet, the specific content is as follows

Created an MFC shared-link library with only such an addition

_declspec (dllexport) int add (int a,int b) {

return a+b;

}

Then create an MFC EXE, select the dialog box, add a button, the event inside

extern int Add (int a,int b);

void Cdlltestdlg::onbnclickedbtnadd ()

{

CString str;

m_xx= Add (1,35);

UpdateData (FALSE);

}

Now the problem is click Build-Build Solution, in the project directory under the Dug, click on the generated EXE file to run correctly,

But in vs2010, pressing F5 will prompt you:

The answer on the Internet is this:

DLL and the actually called Project, all in the  same solution, I removed the DLL project.
Then I will follow this content to operate, the results will be immediately.    

The tragic thing is still back, I want to reproduce the error type: Result I reload the project, the error does not appear, there is a chance that everyone can experiment, in short, dynamic link library is not good to do AH!!!!!

DLL loading always goes wrong and the display fails to load