JNA problema estranho

/**
     * Classe interface onde serão declarados os métodos contidos na dll Tenha o
     * cuidado de lembrar que, diferente do Delphi, Java é case sensitive.
     */
    public interface DLL extends Library {

        public String CalcularMediaParcial(String caminho,
                String GUID, int idEmpresa, int idGrupoEmpresa, int idUsuario, int idPeriodoLetivo,
                int idCurso, int idCiclo, int idSerie, int idFaseCalendario, int idProfessor, int idDisciplina,
                int idTurma);

        public void LiberarRecursos();
    }

    /**
     * Método que tentará encontrar a dll.
     */
    public static DLL loadAdMediaParcialDLL() {
       
        try {
            //Tenta carregar a DLL em c:\windows\system32
            return (DLL) Native.loadLibrary("AdMediaParcial.dll", DLL.class);
        } catch (UnsatisfiedLinkError e) {
            
                logger.error("AdMediaParcial.dll Não Encontrada!" + ex);
                return null;
            
        }
    }

    public synchronized String execAdMediaParcialDLL(String caminho,
            String GUID, int idEmpresa, int idGrupoEmpresa, int idUsuario, int idPeriodoLetivo,
            int idCurso, int idCiclo, int idSerie, int idFaseCalendario, int idProfessor, int idDisciplina,
            int idTurma) {

       
        String retorno = "";

        try {
            if (consultaDll == null) {
                //System.out.println("[CentralApontamentoNotas] manda carregar a dll");
                consultaDll = loadAdMediaParcialDLL();
            }

            if (consultaDll != null) {
            
            //Aqui é que obtenho o retorno do calculo em uma String 
                  retorno = consultaDll.CalcularMediaParcial(caminho,
                        GUID, idEmpresa, idGrupoEmpresa, idUsuario, idPeriodoLetivo,
                        idCurso, idCiclo, idSerie, idFaseCalendario, idProfessor, idDisciplina, idTurma);

               

                consultaDll.LiberarRecursos();

            }

        } catch (Exception e) {
            //System.out.println("ERRO!");
            e.printStackTrace();
        } finally {
            consultaDll.LiberarRecursos();
            System.gc();
        }
        return retorno;
    }

{ $HDR$}
{******************************************************************}
{ Advice POS }
{ }
{ Copyright (c) 2006-2009 Advice System Sistemas Lucrativos Ltda. }
{ }
{******************************************************************}
{}
{ $Log: 137251: AdMediaParcial.dpr
{
{ Rev 1.1 14/09/2012 16:49:06 mvnascimento
}
{
{ Rev 1.0 13/09/2012 16:18:10 mvnascimento
{ Projeto criado com a finalidade de fornecer rotinas do AdvicePOS ao
}
library AdMediaParcial;
{ Important note about DLL memory management: ShareMem must be the
first unit in your library's USES clause AND your project's (select
Project-View Source) USES clause if your DLL exports any procedures or
functions that pass strings as parameters or function results. This
applies to all strings passed to and from your DLL--even those that
are nested in records and classes. ShareMem is the interface unit to
the BORLNDMM.DLL shared memory manager, which must be deployed along
with your DLL. To avoid using BORLNDMM.DLL, pass string information
using PChar or ShortString parameters. }
{ /*************************************************************************/
/*************************************************************************/ }
uses
SysUtils,
ShareMem,
dxGDIPlusAPI,
Classes,
MidasLib,
unt_FechamentoFase,
unt_DmMediaParcial in 'unt_DmMediaParcial.pas' {DmMediaParcial: TDataModule};
{$R *.res}
function CalcularMediaParcial(dirConfigIni: PAnsiChar; GUID: PAnsiChar; idEmpresa,
	idGrupoEmpresa, idUsuario, idPeriodoLetivo, idCurso,
	idCiclo, idSerie, idFaseCalendario, idProfessor,
	idDisciplina, idTurma: Integer): PAnsiChar; stdcall;
	var
	FFMedParcial: TFechamentoFase;
	begin
try
	DmMediaParcial := TDmMediaParcial.Create(dirConfigIni);
	FFMedParcial := TFechamentoFase.Create(DmMediaParcial, idEmpresa, idGrupoEmpresa, idUsuario, GUID
try
	FFMedParcial.PeriodoLetivo := idPeriodoLetivo;
	FFMedParcial.Curso := idCurso;
	FFMedParcial.Ciclo := idCiclo;
	FFMedParcial.Serie := idSerie;
	FFMedParcial.FaseCalendario := idFaseCalendario;
	FFMedParcial.Professor := idProfessor;
	FFMedParcial.Disciplina := idDisciplina;
	FFMedParcial.Turma := idTurma;
	FFMedParcial.CalcConsol := EmptyStr;
	FFMedParcial.TipoFechamento := ftPrevia;
	Result := FFMedParcial.ExecPreviaFechamentoFaseWeb;
finally
	FreeAndNil(FFMedParcial);
	FreeAndNil(DmMediaParcial);
	end;
	except
	on Ex: Exception do
begin
// Retorna o erro especifico p/ quem realizou a chamada
Result := PAnsiChar('ERR-' + Ex.Message);
	end;
	end; // except
	end; // function
procedure LiberarRecursos; stdcall;

	begin
	dxFinalizeGDIPlus;
	end;
	exports
	CalcularMediaParcial,
	LiberarRecursos;
begin
end.

{ $HDR$}
{******************************************************************}
{ Advice POS }
{ }
{ Copyright (c) 2006-2009 Advice System Sistemas Lucrativos Ltda. }
{ }
{******************************************************************}
{}
{ $Log: 137261: unt_DmMediaParcial.pas
{
{ Rev 1.0 13/09/2012 16:18:14 mvnascimento
{ Projeto criado com a finalidade de fornecer rotinas do AdvicePOS ao
}
unit unt_DmMediaParcial;
//*****************************************************************************//
// (untrDMPrincipal e untDmConnection), assim executando o seu initialization
// e gerando problemas de acesso a pacotes e objetos
//*****************************************************************************//
interface
	uses
	SysUtils, Classes, adDBExpress, DBXpress, DB, SqlExpr, AdFunctions, Swsystem;
	type
	TDmMediaParcial = class(TDataModule)
	SQLConnection: TadSQLConnection;
	procedure DataModuleDestroy(Sender: TObject);
private
	{ Private declarations }
public
	{ Public declarations }
	constructor Create(dirIniConfig: String); reintroduce; overload;
	end;
	var
	DmMediaParcial: TDmMediaParcial;
const
	FileIniConfig = 'AdMediaParcial.ini';
	implementation
	{$R *.dfm}
	uses IniFiles;
	constructor TDmMediaParcial.Create(dirIniConfig: String);
	begin
	inherited Create(nil);
if FileExists(dirIniConfig + FileIniConfig) then
	begin
	SQLConnection.ConnectionName := 'AdvConnection';
	SQLConnection.LoadParamsFromIniFile(dirIniConfig + FileIniConfig);
	// Tira a criptografia da senha
	SQLConnection.Params.Values['User_Name'] := Decriptar(SQLConnection.Params.Values['User_Name']);
	SQLConnection.Params.Values['Password'] := Decriptar(SQLConnection.Params.Values['Password']);
try
	SQLConnection.Open;
	except
	on E: Exception do
	raise Exception.Create()
	end;
	end
else
	begin
	raise Exception.Create();
	end;
	end;
	procedure TDmMediaParcial.DataModuleDestroy(Sender: TObject);
	begin
	SQLConnection.CloseDataSets;
	SQLConnection.Close;
end;
end.