trying to get the filename in delphi but...

hi everybody...

i`m trying to build a dll for mirc wich gives me some information about bsplayer. everything works pretty fine but the filename gets me ill :(

my source for that part:

function avl_BSP_GET_FILE_NAME(mWnd: hWnd; aWnd: hWnd; Data: PChar; Parms: PChar; Show: Boolean; NoPause: Boolean ):integer; export; stdcall;
var
cds:TCOPYDATASTRUCT;
buf:array[0..MAX_PATH-1] of char;
adr:pointer;
FILENAME : string;
begin
adr:=@buf;
cds.dwData:=SendMessage(FindBsplayer,WM_COPYDATA,a ppHWND,lParam(@cds));
cds.lpData:=@adr;
cds.cbData:=4;
strcopy(data,PChar(FILENAME));
result:=3;
end;

Borland Delphi Version 15.0
Copyright (c) 1983,2002 Borland Software Corporation
avl.bsplayer.dpr(315) Error: Undeclared identifier: 'appHWND'
avl.bsplayer.dpr(332)

since i`m not that advanced in delphi that gets me crazy hehe.
maybe someone is here who knows how to do this.

thanks

fugi

p.s.: i know that filename is empty, i just had no chance to try to get that out of the buf :(