Do you have
BROWSERREP ON and/or
BROWSERSUM ON in your config? (Or are you running from the command line with
+b?) You may want to edit your question and include your Analog config and/or your command-line invocation of it.
FWIW, Analog's documentation suggests that it won't parse IIS files that contain referer and browser info:
There are also various third-party extensions to the Microsoft format to include, for
example, the browser and referrer. But they all do it in different ways, so analog can't
automatically diagnose them, and again, you need to write a LOGFORMAT command for them.
That said, explicitly setting
LOGFORMAT to one of:
MICROSOFT-NA (North American date format),
MICROSOFT-INT (international date format),
MS-EXTENDED (Microsoft's attempt at extended format),
MS-COMMON (a buggy version of common format in some versions of Microsoft software)
may get you what you want. (All descriptions copied from Analog's documentation.)