If you're using tokens in the "Variable Name / Token" field, the input is considered to be literal text, not a variable name.
You're currently checking whether literal text has been set, which I suppose it has.
To retrieve the value of a variable within that field, you'll want to wrap the input in another "{TXT:}" token, which will return the literal value of the variable whose name is represented by the other tokens.
Note, this again returns a literal value, therefore the "Has Been Set" operator does not apply.
Instead, you'd want to compare against the literal text "Not set" (this does mean there is no method for differentiating between a variable set to the literal text "Not set", or a variable that actually has not been set, when using tokens to derive a variable name)