Lookup Question - text with list error

[antproberts]

I am building a proof of presence application that uses NFC tags.

I have two tables Tags and Scans.  

Tags table lists all of the tags attributed to a site and contains tag name (text) and location (Lat Long)

The Scans table also contains tag name and location with the same column types.  Basically when a tag is scanned the tag name is populated into the form, I then need an expression to pull the location for that tag over to the location column in the Scans table.  I have tried lookup however this presents errors as I it says I am comparing text with list.

Please can someone help with an expression for this?