How can I copy a folder ?

I want to write a function that can cope an existing folder to a new place
with a new name. My code is this:

function CopyFolder(const src,dest : string ):integer;
var
Info: TSHFileOpStruct;
begin
with Info do begin
   Wnd := 0;
   wFunc := FO_COPY;
   pFrom := pChar(Src);
   pTo := pChar(dest);
   fFlags := 0;
end;
try
  result:= SHFileOperation(Info);
except
end;
end;

However, when I execute the code above, I am prompted with a dialog
"The destination cannot support long file names"
And it asks for a shorter file name.

What am I doing wrong?
Is there any other way around, for copying folders?