Can't Edit my Instructable!

I recently started work on an instructable for the upcoming Halloween contest. It was not finished so I saved it and attempted to continue it it today. when I hit the edit button I got the following:

ERROR 500: java.lang.NullPointerException

Exception

java.lang.NullPointerException
at com.instructables.webapp.instructable.LockingEditInstructableAction.prepare(LockingEditInstructableAction.java:69)
at com.instructables.servlet.ActionServlet.prepare(ActionServlet.java:163)
at com.instructables.servlet.ActionServlet.doGet(ActionServlet.java:276)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:115)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:92)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:106)
at com.caucho.filters.GzipFilter.doFilter(GzipFilter.java:208)
at com.instructables.filter.FilterWrapperFilter.doFilter(FilterWrapperFilter.java:48)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.instructables.filter.SecurityFilter.doFilter(SecurityFilter.java:211)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.instructables.filter.HibernateSessionRequestFilter.doFilter(HibernateSessionRequestFilter.java:70)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:173)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:274)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:511)
at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:520)
at com.caucho.util.ThreadPool.run(ThreadPool.java:442)
at java.lang.Thread.run(Thread.java:619)

Please help.