win32 api & lib issue

[Peter Hu via Digitalmars-d-learn]

Greetings!

From time to time I encountered issues on the subjected after I 
upgraded my dmd package.Given below code :

import core.sys.windows.windows;
import core.sys.windows.commdlg;
import core.sys.windows.winuser;

extern(Windows) BOOL GetOpenFileNameW(LPOPENFILENAMEW);
extern(Windows) int MessageBoxW(HWND,LPCWSTR,LPCWSTR,UINT);

    void main()
    {
        wchar[256] fileName;
        fileName[0]=0;
        OPENFILENAMEW ofn;
        
        ofn.lStructSize=OPENFILENAMEW.sizeof;
        ofn.lpstrFilter=
        "Text Files\0*.txt\0 D files\0*.d;*.di\0\0"w.ptr;
        ofn.lpstrFile=fileName.ptr;
        ofn.nMaxFile=fileName.length;
        if(GetOpenFileNameW(&ofn))
        {
                MessageBoxW(null,ofn.lpstrFile,"File Selected:"w.ptr,0);      
        }
    }

The compiler failed to build this small program.It complains 
GetOpenFileNameW & MessageBoxW are unresolved external symbol.

DMD 2.103+VS Community 2015+Win10 64bit.

estwinapi.obj : error LNK2019: 无法解析的外部符号 
_GetOpenFileNameW@4，该符号在函数 __Dmain 中被引用
testwinapi.obj : error LNK2019: 无法解析的外部符号 _MessageBoxW@16，该符号在函数 
__Dmain 中被引用
testwinapi.exe : fatal error LNK1120: 2 个无法解析的外部命令

Error: linker exited with status 1120

Appreciated any help on figuring me out what the issue is and how 
to fix it.