PR Workflow


I have a query regarding PR workflow in Ax 2009. I am facing problem with Notification populating at the end of Assignee. Workflow installed successfully, Workflow configuration done with single approval & assigned to only one use (user based approval).

I m having 3 problems:

  1. In event viewer it is giving the following problem:

Exception thrown in SysWorkflowEventDispatcher-onAcknowledgeWorkflowActivation SysWorkflowEventDispatcher-raiseWorkflowActivationEvent : Web service failed: workflow id WFI000021 The request failed with HTTP status 503: Service Unavailable.

2)I m only getting notification saying that “Web service failed: workflow id WFI000001”.

  1. When i m trying to submit PR it is giving the class error:
Error executing code: Wrong argument type for function.

(S)\Classes\WorkflowDocumentField\substitutePlaceholder - line 130
(S)\Classes\WorkflowDocumentField\substitutePlaceholderAsUser - line 22
(S)\Classes\SysWorkflowFormControls\getActionBarContentForSubmit - line 41
(C)\Classes\SysWorkflowFormControls\showSubmit - line 18
(C)\Classes\SysWorkflowFormControls\updateControls - line 29
(C)\Classes\SysSetupFormRun\updateWorkflowControls - line 4
(C)\Forms\PurchReqTable\Data Sources\PurchReqLine\Methods\write - line 29
(C)\Classes\SysSetupFormRun\task - line 20

Workflow Due date expirations and  Workflow Message processing are running. and I have configured the system service accout 
And workflow runtime url is also working

try to compile all the classes