PO Workflow error

[sgeeta]

Hi All

I am getting this workflow error has any one had this issue can some one advice what sets to take.
An Error occurred in the following Workflow.

Item Type = POAPPRV
Item Key = 55833-178075
User Key =

Error Name = WF_INVALID_ROLE
Error Message = 396: Invalid role name 'REQ_USERS_WF'
Error Stack =
Wf_Directory.AddUsersToAdHocRole(REQ_USERS_WF, "WOODSR")
Wf_Engine_Util.Function_Call(CUSTOM_CREATE_ROLE.CREATE_ASSIGN, POAPPRV, 55833-178075, 47039, RUN)

Activity Id = 47039
Activity Label = MAIN_POAPPRV_PROCESS:CREATE_ROLES
Result Code = #EXCEPTION
Notification Id =
Assigned User =

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Thanks