Work History work items is empty

Anyone who has an idea what particular class data on the datasource used by the work items grid in workflow history. I am working on workflow, after I click on the [SUBMIT] button (changes workflow status from not submitted to submitted), of course this would be for approval, when I check my workflow history and filter all pending items, I notice that the work items is empty. Any idea from you guys how am I going to deal with this issue?

What do you mean by that?

Sorry, I mean, I’d like to know what particular class is being used in order to insert record on work items.

You can find it with the help of cross references,