Where clause in lookup table

Hi everybody!

I want to filter my dropdown menu using a dynamic query.

In my page there is a "ProjectName", "IDProject", "ContractName".

The contract name field is a dropdown menu.

I want that it is filtered using all the contracts having the corresponding IDProject in the same record.

So I'm trying to use in the Edit as "lookup wizard" the where clause:
I tryed

1. " where ContractPrj = "&rs("IDProject") --> KO
   
2. " where ContractPrj = "&session("IDProject") --> KO
   
3. " where ContractPrj = "&rstmp("IDProject") --> KO
   How must I write the IDProject to use in the query?
   Thanks