Exception when deleting attachment on Import page

        Error number 0 in 11: Uncaught exception
Wrapped Exception: null
com.xpn.xwiki.XWikiException: Error number 0 in 11: Uncaught exception
Wrapped Exception: null
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:159)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:596)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:428)
	at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:830)
	at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:121)
	at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
	at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:471)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:568)
	at org.mortbay.http.HttpContext.handle(HttpContext.java:1565)
	at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:633)
	at org.mortbay.http.HttpContext.handle(HttpContext.java:1517)
	at org.mortbay.http.HttpServer.service(HttpServer.java:954)
	at org.mortbay.http.HttpConnection.service(HttpConnection.java:816)
	at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:983)
	at org.mortbay.http.HttpConnection.handle(HttpConnection.java:833)
	at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:244)
	at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:357)
	at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:534)


Wrapped Exception:

java.lang.NullPointerException
	at com.xpn.xwiki.store.XWikiHibernateAttachmentStore.deleteXWikiAttachment(XWikiHibernateAttachmentStore.java:292)
	at com.xpn.xwiki.store.XWikiHibernateAttachmentStore.deleteXWikiAttachment(XWikiHibernateAttachmentStore.java:213)
	at com.xpn.xwiki.doc.XWikiDocument.deleteAttachment(XWikiDocument.java:2018)
	at com.xpn.xwiki.web.DeleteAttachmentAction.action(DeleteAttachmentAction.java:49)
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:143)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:596)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:428)
	at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:830)
	at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:121)
	at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
	at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:471)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:568)
	at org.mortbay.http.HttpContext.handle(HttpContext.java:1565)
	at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:633)
	at org.mortbay.http.HttpContext.handle(HttpContext.java:1517)
	at org.mortbay.http.HttpServer.service(HttpServer.java:954)
	at org.mortbay.http.HttpConnection.service(HttpConnection.java:816)
	at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:983)
	at org.mortbay.http.HttpConnection.handle(HttpConnection.java:833)
	at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:244)
	at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:357)
	at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:534)