Visual Calculations/ DAX Measure - Total Incorrect on Table Visual

Hi All,

I am reaching out for help on DAX. I know this a common issue in this forum. I tried different approaches but none of them gets me to the solution. I tried to use visual calculations and switched to DAX measure but neither of them is working.

My DAX measure is not removing the rowcontext filter for the totals, the result I am looking is my total should be the sum of values in the column. I have attached the sample of my data and dax 
My expected result for this selection should be (-115) which is sum of values in Availability, however the current result is based off the totals. 

DAX:

 SUMX(

    'product tbl',

    VAR _Key = 'product tbl'[Key]

    VAR _PO_QTY = CALCULATE(SUM(Availability[PO_Qty]))

    VAR _PREBOOK_QTY = CALCULATE(SUM(Availability[PreBookQty]))

    VAR _PLANTED_QTY =

                        SUMX(

                            FILTER('Dynamic', 'Dynamic'[plantState] = "Realized"),

                            'Dynamic'[quantity]

                        ) + CALCULATE(SUM(Overdue[quantity]))

    VAR _PLANNED_QTY =

                        SUMX(

                            FILTER('Dynamic', 'Dynamic'[planState] = "Budget"),

                            'Dynamic'[quantity]

                        ) + CALCULATE(SUM('External Bookings'[Booked Qty]))

    RETURN

        IF(

            NOT(ISBLANK(_PLANTED_QTY)),

            _PLANTED_QTY - _PO_QTY - _PREBOOK_QTY,

            _PLANNED_QTY - _PO_QTY - _PREBOOK_QTY

        )

)

Any help is much aprreciated!!

Thanks in advance.