Created a new project server workflow with log statement and workflow is not getting start. In the log file getting the below error. please suggest

Load Workflow Class: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.   

at Microsoft.SharePoint.Workflow.SPWinOeHostServices.EnsurePluggableServices(SPSite site, SPWorkflowExternalDataExchangeServiceCollection services, ExternalDataExchangeService existingServices)   

at Microsoft.SharePoint.Workflow.SPWinOeHostServices..ctor(SPSite site, SPWeb web, SPWorkflowManager manager, SPWorkflowEngine engine)     -

-- End of inner exception stack trace ---   

at System.RuntimeMethodHandle.InvokeMethod(Object target, Objecta] arguments, Signature sig, Boolean constructor)   

at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Objectr] parameters, CultureInfo culture)   

at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Objectn] args, CultureInfo culture, Objectn] activationAttributes, StackCrawlMark& stackMark)   

at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object ] args, CultureInfo culture, Objectr] activationAttributes)   

at System.Reflection.Assembly.CreateInstance(String typeName, Boolean ignoreCase, BindingFlags bindingAttr, Binder binder, Objectt] args, CultureInfo culture, Objectl] activationAttributes)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.LoadPluggableClass(String classname, String assembly, Objecta] parame

Please suggest.