Form inside VelocityPanel throws WicketRuntimeException: Unable to find the markup for the component.

I am trying to have a Form inside a VelocityPanel, but I get the following Exception:

WicketMessage: Unable to find the markup for the component. That may be due to transparent containers or components implementing IComponentResolver: [MarkupContainer [Component id = form, page = simplevelocity.SimpleVelocityPage, path = 3:velocity:form.MyForm, isVisible = true, isVersioned = true]]

Root cause:

org.apache.wicket.WicketRuntimeException: Unable to find the markup for the component. That may be due to transparent containers or components implementing IComponentResolver: [MarkupContainer [Component id = form, page = simplevelocity.SimpleVelocityPage, path = 3:velocity:form.MyForm, isVisible = true, isVersioned = true]]
at org.apache.wicket.MarkupFragmentFinder.find(MarkupFragmentFinder.java:118)
at org.apache.wicket.Component.locateMarkupStream(Component.java:3584)
at org.apache.wicket.Component.getMarkupAttributes(Component.java:1359)
at org.apache.wicket.markup.html.form.Form.getMethod(Form.java:1310)
at org.apache.wicket.markup.html.form.Form.onComponentTag(Form.java:1457)
at org.apache.wicket.Component.renderComponent(Component.java:2400)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1354)
at org.apache.wicket.markup.html.form.Form.onRender(Form.java:1588)
at org.apache.wicket.Component.render(Component.java:2266)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1240)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1370)
at org.apache.wicket.velocity.markup.html.VelocityPanel.onComponentTagBody(VelocityPanel.java:228)
at org.apache.wicket.Component.renderComponent(Component.java:2429)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1354)
at org.apache.wicket.Component.render(Component.java:2266)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1240)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1370)
at org.apache.wicket.Page.onRender(Page.java:1442)
at org.apache.wicket.Component.render(Component.java:2266)
at org.apache.wicket.Page.renderPage(Page.java:891)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.respond(BookmarkablePageRequestTarget.java:231)
at org.apache.wicket.request.AbstractRequestCycleProcessor.respond(AbstractRequestCycleProcessor.java:103)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1100)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1169)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1245)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:489)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:354)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:194)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445)
at java.lang.Thread.run(Thread.java:595)

I also have a Label inside the VelocityPanel, which works fine.