First off, irregardless what it says in the model's loading screen and drop down menu, it's properly referred to as an "Su-27", not an "SU-27"....just thought you'd like to know
Naming conventions and in-service dates would be the first two items I'd check.
In regards to naming conventions, keep in mind that AA-8x = R-60x, AA-10x = R-27x, AA-11x = R-73x, etc. See what they're named in your weapons folders.
In regards to service dates, There were no Archers (AA-11) commonly available before 1989, and no Adders until after 1990-1993. AA-8 Aphids were available since the mid-1970s, with the all-aspect Aphid-B being used on both MiG-29s and Su-27s from 1984 onwards (the intro date for both airframes).