ParameterIdentifierTuple returns empty strings

[Andre Pany via Digitalmars-d-learn]

Hi,

I need to retrieve the parameter identifier but only empty 
strings are returned:
tuple("", "")
``` d
alias fpt = extern(C) nothrow void function(int a, int b);

void main()
{
    import std.traits : ParameterIdentifierTuple;
    pragma(msg, ParameterIdentifierTuple!(fpt));
}
```

Where is here the error?

Kind regards
André