Problem about QTimer

[pawer]

I have several classes in my program, one of them is the main GUI and other is an XML-RPC (from XML-RPC for C/C++) class that have several methods. All thinks goes ok, but when I start the QTimer in the GUI class from the XMLRPC clas it says "QTimer can't be stop/started from other thread". If I put signals and slots does nothing. WTF?

cambiaTimer::cambiaTimer ( rssani_lite *rss, QObject *parent ) :  QObject ( parent ),rpc_ani ( rss )  {
	connect ( this,SIGNAL ( cambiarTimer ( int ) ), rss, SLOT ( cambiaTimer ( int ) ) );
}
 
void cambiaTimer::execute ( xmlrpc_c::paramList const& paramList,xmlrpc_c::value *   const  retvalP ) {
 
	emit cambiarTimer ( 1 );
	std::cerr << "RPC llamada" << std::endl;
	*retvalP = xmlrpc_c::value_int ( 0 ) ;
}

cambiaTimer::cambiaTimer ( rssani_lite *rss, QObject *parent ) :  QObject ( parent ),rpc_ani ( rss )  {
	connect ( this,SIGNAL ( cambiarTimer ( int ) ), rss, SLOT ( cambiaTimer ( int ) ) );
}

void cambiaTimer::execute ( xmlrpc_c::paramList const& paramList,xmlrpc_c::value *   const  retvalP ) {

	emit cambiarTimer ( 1 );
	std::cerr << "RPC llamada" << std::endl;
	*retvalP = xmlrpc_c::value_int ( 0 ) ;
}

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void rssani_lite::cambiaTimer(int tiempo) {
	qDebug() << "Timer cambiado a : " << tiempo << endl; 
	this->tiempo = tiempo;
	timer.start ( tiempo * 60 * 1000 );
}

void rssani_lite::cambiaTimer(int tiempo) {
	qDebug() << "Timer cambiado a : " << tiempo << endl; 
	this->tiempo = tiempo;
	timer.start ( tiempo * 60 * 1000 );
}

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class rssani_lite : public QObject {
	Q_OBJECT
 
public:
	rssani_lite ( QObject* parent = 0);
	~rssani_lite();
 
public slots:
	void cambiaTimer(int tiempo);
        ....
}

class rssani_lite : public QObject {
	Q_OBJECT

public:
	rssani_lite ( QObject* parent = 0);
	~rssani_lite();

public slots:
	void cambiaTimer(int tiempo);
        ....
}

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Thanks in advance.