Hi Sam
Solved it with a Switch Function and Disconnected Table
Period VALUE:=IF(HASONEVALUE(Periods[Period Name]),
SWITCH(VALUES(Periods[Period Name]),
"W-5",CALCULATE([Availability],Dates[MonthNameShort]="W-5"),
"W-4", CALCULATE([Availability],Dates[MonthNameShort]="W-4"),
"W-3", CALCULATE([Availability],Dates[MonthNameShort]="W-3"),
"W-2", CALCULATE([Availability],Dates[MonthNameShort]="W-2"),
"W-1", CALCULATE([Availability],Dates[MonthNameShort]="W-1"),
"B1", [B1],
"Jan", CALCULATE([Availability],Dates[MonthNameShort]="Jan"),
"Feb", CALCULATE([Availability],Dates[MonthNameShort]="Feb"),
"Mar", CALCULATE([Availability],Dates[MonthNameShort]="Mar"),
"Apr", CALCULATE([Availability],Dates[MonthNameShort]="Apr"),
"May", CALCULATE([Availability],Dates[MonthNameShort]="May"),
"Jun", CALCULATE([Availability],Dates[MonthNameShort]="Jun"),
"Jul", CALCULATE([Availability],Dates[MonthNameShort]="Jul"),
"Aug", CALCULATE([Availability],Dates[MonthNameShort]="Aug"),
"Sep", CALCULATE([Availability],Dates[MonthNameShort]="Sep"),
"Oct", CALCULATE([Availability],Dates[MonthNameShort]="Oct"),
"Oct", CALCULATE([Availability],Dates[MonthNameShort]="Oct"),
"Nov", CALCULATE([Availability],Dates[MonthNameShort]="Nov"),
"Dec", CALCULATE([Availability],Dates[MonthNameShort]="Dec"),
"B2", [B2],
"CMCY", [Mth_CY_Act],
"CMB", [Mth_CY_Bud],
"CMPY", [Mth_PY_Act],
"YTDCY", [Ytd_CY_Act],
"YTDB", [Ytd_CY_Bud],
"YTDPY", [Ytd_PY_Act],
BLANK()
),[Total_Amount])
Cheers