Calculated column rows do not return values for all rows

Hi,

I have 2 tables - Currency & Sales and they are connected by many to many relationship.

I have created a calculated column in Sales table, and it returns value for only one condition, where the period is equal to '20214'. For other rows, where the period is <> 20214, the values are blank. Below is my table structure & the DAX

Table Currency -

Field     LCurrency     FCurrency     FXRate     Type     Period

yyyym   EUr               GBp              0.8545      AVRS    20214

             USd              GBp              1.1684      AVRS    20214

             JPy                Eur               0.8808      RNMJ   20214

Table Sales

Field     Item     Currency     Sales     Period     Calculated Column Value

yyyym  0123     USd            10000    20214      8558.712

            4567     USd              8000     20213     BLANK, value should be 6846.97

            8787     EUr               2000     20216     BLANK, value should be 2340.55

DAX is:

'SALES'[Sales] *

DIVIDE(1,

   CALCULATE(

      FIRSTNONBLANK('Currency'[FXRate], TRUE() ),

          FILTER(

             'Currency'

             'Currency'[LCurrency] = 'Sales'[Currency] &&

             'Currency'[FCurrency] = "GBP" &&

             'Currency'[Type] = "AVRS" &&

            'Currency'[Period] = "20214")

)

)

Appreciate your help on this please.

Thanks,