Hi
When I call a rpc service send the error, and I dont know what happen.

Code:
Error al obtener los productos
500 The call failed on the server; see server log for details
com.google.gwt.user.client.rpc.StatusCodeException: 500 The call failed on the server; see server log for details
	at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:209)
	at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287)
	at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
	at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
	at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:167)
	at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:326)
	at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:207)
	at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:132)
	at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
	at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
	at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
	at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
	at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:214)
	at sun.reflect.GeneratedMethodAccessor45.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
	at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
	at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:167)
	at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281)
	at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531)
	at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
	at java.lang.Thread.run(Thread.java:619)
Code:
 <!-- Hacemos uso de las anotaciones para scan de todos los servicios -->
	<context:component-scan base-package="mx.grupocp.simmf"/>

@Service("catalogoServiceGwt")
public class CatalogoServiceGwtImpl implements CatalogoServiceGwt{

	@Override
	public void sayHola() {
		System.out.println("Hola Mundo");
	}

}

-------------------------------------------------

@RemoteServiceRelativePath("springGwtServices/catalogoServiceGwt" )
public interface CatalogoServiceGwt extends RemoteService{
	
	void sayHola();
	//List<CatalogoDM> getProductos();
}


-------------------------------------------


public interface CatalogoServiceGwtAsync {

	void sayHola(AsyncCallback<Void> callback);
}

---------------------------------------------------------

public AfiliacionGui() {
		init();
		serviceCatalogo.sayHola(new AsyncCallback<Void>() {
			
			@Override
			public void onSuccess(Void result) {
				result.toString();
			}
			
			@Override
			public void onFailure(Throwable caught) {
				System.out.println("Error al obtener los productos\n" + caught.getMessage());
				caught.printStackTrace();
				
			}
		});
	}
Code:
<module rename-to='simmf' >
	<inherits name="com.extjs.gxt.ui.GXT"/>
	<inherits name="com.extjs.gxt.desktop.WebDesktop" />
	<inherits name="com.google.gwt.user.User"/>

	<entry-point class="mx.grupocp.simmf.client.SIMMF"/>
</module>


------------------------------------


<web-app>
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>
			classpath:/META-INF/PersistenceAppCtx.xml,
			classpath:/META-INF/ServicesAppCtx.xml,
			classpath:/META-INF/TxAppCtx.xml,
			classpath:/META-INF/GWTServicesAppCtx.xml,
			classpath:/META-INF/WSAppCtx.xml
		</param-value>
	</context-param>

	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	
	<!-- Servlet que mapea las peticiones de GWT -->
	<servlet>
		<servlet-name>springGwtRemoteServiceServlet</servlet-name>
		<servlet-class>org.spring4gwt.server.SpringGwtRemoteServiceServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>springGwtRemoteServiceServlet</servlet-name>
		<url-pattern>/simmf/springGwtServices/*</url-pattern>
	</servlet-mapping>

	<!-- Default page to serve -->
	<welcome-file-list>
		<welcome-file>SIMMF.html</welcome-file>
	</welcome-file-list>

</web-app>
Please help me