How to setup an alert if a string is present in logs?

[jangaraj]

Warning when creating an Alert: "Expression warning - 1 items dropped from union(s): ["${B} > 1.000000": (1.000000: {})]"

Hi, I’m getting this warning when I try to add an alert. I simply want to create an alert when there’s a new log that contains the word “login.” Quite simple but it doesn’t work, even if there are “login” word inside the logs in the last few minutes, Loki finds “No data” and the warning: [SCR-20240603-ufbm] What I’m doing wrong? Thanks