VelocityServlet : Error processing the template

org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getContentUri' in  class net.sf.scmwebgui.CtxURI threw exception class java.lang.NullPointerException : null
org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getContentUri' in class net.sf.scmwebgui.CtxURI threw exception class java.lang.NullPointerException : null at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:309) at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:207) at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:250) at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271) at org.apache.velocity.Template.merge(Template.java:296) at org.apache.velocity.servlet.VelocityServlet.mergeTemplate(VelocityServlet.java:448) at org.apache.velocity.servlet.VelocityServlet.doRequest(VelocityServlet.java:387) at org.apache.velocity.servlet.VelocityServlet.doGet(VelocityServlet.java:333) at javax.servlet.http.HttpServlet.service(HttpServlet.java:689) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at net.sf.scmwebgui.AbstractCacheFilter.applyCache(AbstractCacheFilter.java:196) at net.sf.scmwebgui.AbstractCacheFilter.doFilter(AbstractCacheFilter.java:157) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:704) at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:590) at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:510) at net.sf.scmwebgui.ControllerServlet.process(ControllerServlet.java:214) at net.sf.scmwebgui.ControllerServlet.doGet(ControllerServlet.java:136) at javax.servlet.http.HttpServlet.service(HttpServlet.java:689) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at net.sf.scmwebgui.AccessFilter.applyAccessFilter(AccessFilter.java:246) at net.sf.scmwebgui.AccessFilter.doFilter(AccessFilter.java:156) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214) at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520) at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152) at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137) at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118) at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929) at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705) at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683) at java.lang.Thread.run(Unknown Source)