Select rows from table 1 that don't exist on table 2 where the id of table 1 equals the selected id

[Gigi12]

Hi!

I'm a little bit confused with this. 
I'm trying to select the column A from table 1 where the table 1 id equals the id selected in the form (it's a ref column); however, I need that the values retrieved don't exist in table 2 (here's where we are going to save the form's results)

I've tried different things without success. 

SELECT(Table 1[A],AND([_THISROW].[Id]=[Id],NOT(IN([A], SELECT(Table 2[A],[_THISROW].[Id]=[Id], TRUE))),TRUE))

I'm not sure what I'm doing wrong.