Configuring custom health check (send string)

I need to configure custom health monitors (http & https) and I'm stuck at configuring the Send string. I have it configured to go to and receive "yes".

When I configured the Send string I used the following which isn't working; GET /sso.companyname/sortingpen/sortingpen.aspx\r\n

I've tried multiple variations and nothing is working.

Thanks in advance for your help!!