Variables works in Label but not in Expression

[Sandy_Liu]

Hi,

I've created 2 variables( v_int_month+v_int_last_month)  in scripts to get the month M and month M-1: 

set v_int_month=
if (%(v_t_f_selection_on_int) = 0,num(Monthname(Max(Date([Date Initiated],'YYYY/MM/DD')))),num('Initiated Month'));
Let v_int_month = Replace('$(v_int_month)','%','$');

set v_int_last_month=if (%(v_t_f_selection_on_int) = 0,num(Monthname(Max(Date([Date Initiated],'YYYY/MM/DD')),-12)),num(Monthname('Initiated Month',-12)));
Let v_int_last_month = Replace('$(v_int_last_month)','%','$');

When I applied it to the set analysis, the v_int_last_month works in Lable but NOT in Expression:

• Here's my set analysis in Lable: 

='MtoM'&' '&'($(=Monthname($(=v_int_month)))'&' vs '&'$(=Monthname($(=v_int_last_month))))'

• And in Expressoin:

=count({<
[a]={'xxxx'},
[b]={"*"},
[Initiated Month]={'$(=$(v_int_month))'}
>} distinct [ID])
-
(count({<
[a]={'xxxx'},
[b]={"*"},
[Initiated Month]={'$(=$(v_int_last_month))'}
>} distinct [ID]))

Do you know where is the probleme and how to solve it?

Thanks,

Sandy