Calculated columns in functions

I am trying to use a calculated column in a function but the field is not accessible.

I have a web call to pass an address as part of a function that returns Latitude and Longitude. However when I try to create the new column based on the function the filed I need to pass in is not one of the options. It only shows the actual table coumns address1, city, state, zip.

I have concatenated all this into one field called FullAddress, but FullAddress is not an option to pass.

How can I use the concatenated field to ensure I get the lat & long I need?