Internal constraint exception

[447_J_U_S_SANDEEP]

Hai
when I run the project, some error is getting.
Error ERROR Validation Error Internal constraint exception while running constraint with name ‘Constraint’ against activity of type System.Activities.Statements.Sequence with name ‘Sequence’. Exception was: System.NullReferenceException: Object reference not set to an instance of an object.
at System.Activities.WorkflowApplication.Invoke(Activity activity, IDictionary2 inputs, WorkflowInstanceExtensionManager extensions, TimeSpan timeout) at System.Activities.WorkflowInvoker.Invoke(Activity workflow, IDictionary2 inputs)
at System.Activities.Validation.ActivityValidationServices.RunConstraints(ChildActivity childActivity, ActivityCallStack parentChain, IList1 constraints, ProcessActivityTreeOptions options, Boolean suppressGetChildrenViolations, IList1& validationErrors) Selectors/Automate AnyTeller application.xaml

please help me.