How set exchange rate date through data query in agent works for invoice?

Summary: I am trying to set exchange rate date using a query to pick existing exchange rate date in the invoice through an agent. But while executing the query it is giving me 'Invalid column index' error leading to agent failure.

Note : The saved query is returning result in the sql servlet and in the assign variable as well.

Can you please explain where exactly it is going wrong or how we can set exchange rate date using a data query.

Content (required): I am trying to set exchange rate date using a query to pick existing exchange rate date in the invoice through an agent. But while executing the query it is giving me 'Invalid column index' error leading to agent failure.