It's hard to picture exactly what you've tried to set up from your first post.
"I want the subsummary report to look like this:
Location: Count no. of visits: Count No. of clients:
So far, I have only managed the no. of visits part. I have defined summary fields 'count no. of visits' which counts 'location' . I have tried to add 'count no. of clients' which counts CLient ID. However, when I sort by location, the report shows me equal values for both."
Did you use a sub summary part for this? How did you set it up?
If you want to re-arrange a summary report to show different breakdowns and subtotals based on how you sorted the records, you can do this by defining different sub-summary parts with different "sorted by" settings--but I'm not sure if that's what you need here or not.
You may already know what's in the following thread or it may be what you need:
Here's a link to a simple tutorial on setting up summary reports that you may find useful:
Creating Filemaker Pro summary reports--Tutorial