Running Total based on two values from different tables.

hi mgiusto 

Please try this

Step1 : Created tables based on data shared by you, please note that I have kept all datatypes as whole number except date which is Date Datatype. I have not linked these two tables in data model.

Step2 : 

Create this measure.

On Hand =

VAR _SelOrg = SELECTEDVALUE(Orders[org])

VAR _selCode = SELECTEDVALUE(Orders[code])

VAR _SelDate = SELECTEDVALUE(Orders[Date])

VAR _OnHandQty = SELECTCOLUMNS(FILTER(OnHand, OnHand[org] = _SelOrg && OnHand[code] = _selCode), "@OnHand", OnHand[on_hand])

VAR _SumQty = CALCULATE( SUM(Orders[ord_qty]), REMOVEFILTERS(), SUMMARIZE(Orders, Orders[org], Orders[code]), Orders[Date] <= _SelDate)

RETURN _OnHandQty - _SumQty