Process stage linked to Opportunity into SSRS report

Hi guys,

Thanks again for all the help so far. I'm doing an SSRS report (using SQL, on prem 2015) for Opportunities and there is a requirement to pull the stage from the business process flow.

I've managed to pull a dataset for FilteredProcessStage (Processstage) which has a stagename field, so I did an expression of =lookup(fields!processid.Value, fields!processid.Value, fields!stagename.Value, "Processstage") but this just pulls the same stage (the first one), not the one related to the opportunity.

I'm missing something, but I can't see what! Any help greatly appreciateD!