vb 调用 DELPhi Dll 返回空值？怎么回事？

Delphi DLL编码：

procedure gncx(var sqlstr,zthstr,ctstr,anstr:pchar;out jg:Pchar);stdcall;
var
   fhjg:widestring;
   sqllj,zth,ctmc,anbh,ls:string;
   th:thandle;
   tf:Tjsjg;
begin
sqllj:=strpas(sqlstr);
zth:=strpas(zthstr);
ctmc:=strpas(ctstr);
anbh:=strpas(anstr);
if wokao(sqllj,zth)=false then begin
   showmessage('该公司无权使用该功能，请确认是否为正版！');
   exit;
end;
fhjg:='';
th:=loadlibrary(pchar('C:\U8add\'+trim(ctmc)+trim(anbh)+'.dll'));
if th>0 then begin
   @tf:=getprocaddress(th,'jsjg');
   try
      if assigned(@tf) then
         fhjg:=tf(pchar(sqllj),pchar(zth));
   finally
      freelibrary(th)
   end;
   end
else begin
   showmessage('调用库文件失败！');
   freelibrary(th);
end;
fhjg:='wokaonima';
move(PChar(fhjg)^,jg^,length(fhjg));
ls:=jg;
showmessage(jg);//这里只能显示“wokao"
end;

VB代码：    Private Declare Unicode Sub gncx Lib "c:\U8add\dcs.dll" (ByRef sqlstr As String, ByRef zthstr As String,
                                                                       ByRef ctstr As String, ByRef anstr As String, ByRef jg As String)

        Call gncx(sql1, zth1, ctmc, gnjmc, jg)
        MsgBox(jg)//这里显示空的