Error while retrive service call.

Hi I am trying to make service.Retrive() call on case entity. we are using MS CRM 2015 On-Premsie. plugin is  registered on SandBox  and it's on post update message

I get this below error message.

incident With Id = 677f1a2d-d557-e611-80f1-005056a65615 Does Not Exist.

I validated, the case with this GUID does exist..

it's simple retrieve call !!

Entity currentCase = service.Retrieve(case.LogicalName, case.Id, new ColumnSet(true));