Passing Variable in Set analysis

[New-Qlik]

Hello ,

I have two variables 

Let vl.product= 'ABC;

Let vl.codes = '1,2';

and i have an expression in table like this 

(sum({$< [Product Name] ={$(vl.product)},[Product Code] ={$(vl.codes )}>}[gross Sales ])

This expression gives me wrong output but if i manually select Product name as ABC and then code it shows correct number.

I have tried putting expression in quotes but no success.

Any idea why its behaving like this.

Thanks

[tresesco]

Possibly a quotation issue. Could you share a sample app that replicates data and issue?