I got this error when I tried to deploy a workflow from K2 Designer for sharepoint.

Task Error: System.Exception: Error occurred adding the feature to the farm. ---> System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> Object reference not set to an instance of an object.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Objectb] parameters)
   at SourceCode.SharePoint.WebServices.K2SPFeatures.AddWorkflowFeature(String featureTitle, String description, Boolean isDefaultForms, K2SPStartForms startForms, K2SPTaskForma] taskForms, K2SPModificationFormi] modForms, String SmartObjectServerConnectionString)
   at SourceCode.Workflow.SharePoint.Common.Features.AddWorkflowFeature(String featureTitle, Boolean isDefaultForms, String FeatureDescription, K2SPStartForms startForms, List`1 taskForms, List`1 modForms, CredentialCache CredCache)
   at SourceCode.DeploymentTasks.SharePoint.WorkflowIntegration.ConfigureEvent.AddFeature(IntegrationObject integration)
   at SourceCode.DeploymentTasks.SharePoint.WorkflowIntegration.WorkflowIntegrationService.Execute(IntegrationObject integration, Boolean testMode, Boolean createDependancies)
   --- End of inner exception stack trace ---
   at SourceCode.DeploymentTasks.SharePoint.WorkflowIntegration.WorkflowIntegrationService.Execute(IntegrationObject integration, Boolean testMode, Boolean createDependancies)
   at SourceCode.DeploymentTasks.SharePoint.WorkflowIntegration.WorkflowIntegrationTask.Execute()

Please help if you can.