How can you add the security ID

I have a log file I would like to add the currently logged in user to.
I want to add it on the ‘Catch’ but it will not show the user.

I have tried adding the connection>security>insert into the Catch and this still does not work.
Am I doing something wrong or can’t the catch deal with this?

The catch step is not used like that.
Here’s how/when to use catch:

In your case all you need to do is to add the security provider you are using for this site, and then add insert step after it … the identity is available when you click the dynamic data picker for the insert value.