Why does stringof not like functions with arguments?

[Jason Brady via Digitalmars-d-learn]

Why does the following code error out with:

app.d(12,10): Error: function app.FunctionWithArguments (uint i) 
is not callable using argument types ()

Code:

import std.stdio;

void FunctionWithoutArguments() {
}

void FunctionWithArguments(uint i) {
}

void main()
{
        writeln(FunctionWithoutArguments.stringof);
        writeln(FunctionWithArguments.stringof);
}