comparison other than equals

The error is that you have an opening brace before the switch argument (before the string tolower command). Remove that and the error should go away.

One more thing, if you use the glob option on switch, you can eliminate the string allocations that are caused by the string range and tolower commands.

This should be equivalent, but likely a bit more optimal.

hen HTTP_REQUEST {
   Parse the fist character in the path
  switch -glob [HTTP::path] {
    "/[a-cA-C]*" {
      pool test1
    }
    "/[d-lD-L]*" {
      pool test2
    }
    "/[m-rM-R]*" {
      pool test3
    }
    "/[s-zS-Z]*" {
      pool test4
    }
    default {
       Requested URI was a leading forward slash only
      pool test5
    }
  }
}

Hope this helps...

-Joe