Can you use an expression created from a prompt in one query to bind to key prompt in a drilling que

I have created a summary query which uses an as of date to select from ledger tables. in that query I have created an expression for the as of date and, based on that date, and expresion to calculate the first date of the year. I want to build a query url which will incluse those dates as propts to the detail query. I am have mapped those expressions to key promps from the detail query. The drill works OK, but when I click on it the prompts appear to be garabage.

Is it possible to use expressions in the prompt map? They show up in the list.