Field Formula (divide values from 2 questions)

Hey,

I'm trying to compute the Conversion Rate, which is calculated by dividing the number of reservations by the number of searches.

I'm able to join the number of searches by day with the number of reservations by day together at a table (in the same row, i.e.: day/#searches/#reservations. But when I create a new column with the field formula, I find an error:
SQL compilation error: error line 1 at position 469 invalid identifier '"source". SEARCH_CHECK_IN_CITY'

Any idea on how to solve this?
Thanks!

Hi @brunoeusebio
Post "Diagnostic Info" from Admin > Troubleshooting.
And post the full stacktrace from Admin > Troubleshooting > Logs.