Hi i get the following error when I upload a document.

Error Details:

An error has occurred in NewWorkflowActivated_Invoked

Error Details: K2.net Server error occured, The request failed with HTTP status 407: Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. ).

at SourceCode.SharePoint.Workflow.Proxy.K2Runtime.StartProcess(K2IntegrationItem k2IntegrationItem, SPWorkflowActivationProperties Properties)

at SourceCode.SharePoint.Workflow.Proxy.MultipleTasksAndUsers.NewWorkflowActivated_Invoked(Object sender, ExternalDataEventArgs e)

Kindly reply if u know why this is happening