Error in set modifier expression

[Stefdev]

Hello everyone,

i need some help. My expression doesnt work and i dont know how to fix it. Maybe the problem is in load script but im not sure. In the first table there is F1,A1,S1,fs and in second table there is f2,a2,s2. F1 and f2 have same values but i cant Join them. So i tried it manually in Selections. 

Sum({<
if(GetSelectedCount(F1)>0,f2={'$(=GetFieldSelections(F1))'},
if(GetSelectedCount(A1)>0,a2={'$(=GetFieldSelections(A1))'}),
if(GetSelectedCount(S1)>0,s2={'$(=GetFieldSelections(S1))'}),
fs={'1'}>}fs)

I also tried GetCurrentSelections but i doesnt work.

Maybe you guys have a different solution or can help me with my expression. I would appreciate it.

Thank you very much in advance!

Stefdev