Measure with specific filter ignored on interaction with table

Hi all,

i have a pivot table (matrix) and a slicer; the slicer interaction with the table is taken so that the table show all dimension values 

and i want to create a measure which calculates count for selected value on slicer; ignoring the header dimension (A,B,C,D)

the figures need to be for A

matrix example

Brand      A         B             C              D

Sales1      10        10           10           10

Sales2      20         20          20           20

Sales3       25         25          25          25

where Sales1, Sales2 and Sales3 for A are 10, 20 & 25

the slicer selection is A

the measure is 

measure =
VAR Brand_selected =
SELECTEDVALUE ( source[Brand] )

RETURN
CALCULATE(count(source[Value], FILTER(source,source[Value]<2 && source[Brand]=Brand_selected)))

can you help me with the correct syntax?

thanks,

Cosmin