Unresolved external symbol

[Ga via Digitalmars-d-learn]

I have the following code:

import std.stdio;
version(Windows)
{
        extern(Windows)
        {
                nothrow
                {
                        alias void *HANDLE;
                        alias HANDLE HDC;
                        int GetDeviceCaps(HDC, int);
                }
        }
}

int main()
{
        int left = GetDeviceCaps(null, 8);

        readln();

        return 0;
}

And I am getting a "error LNK2019: unresolved external symbol 
GetDeviceCaps referenced in function _Dmain"

Why is that? I'm obviously missing something here, because 
another function, GetDC works properly..