hello,
Looks like a syntax issue. You should have 2 or more spaces (or tab for simplicity) between the keyword name and its arguments i.e.
Click Element <<TAB or more than 2 spaces here>> id=show_login
There seems to be a single space in your case (between keyword name and arg) causing the robot framework to believe it as a different keyword (which doesn't exist), and hence the error.
best,
Mukesh