During my last flight to Riga airport (EVRA - Latvia, Eastern Europe) I was going to land on runway 36. I was on my B739 with latest AIRAC 1802.
Per FMC info the ILS frequency for this runway is 108.10 so I put this into my NAV panel.

However after reaching the runway path - localizer hasn't been identified - so obviously I couldn't turn on either VOR LOC or APP.

I started to seek where is the problem. The ILS chart available on Latvia VACC (http://www.lv-vacc.org) on this link:
https://ais.lgs.lv/eAIPfiles/2018_001_01-FEB-2018/data/2018-02-01-AIRAC/graphics/eAIP/4509363_EV_ADC_2_EVRA_24_11_3_EN.pdf

showed me that the frequency is 108.10 - so the conclusion was that I put the correct one in my NAV panel. Moreover this chart seems to be up to date since it has a note "FEBRUARY 2018".

However then I found this site:
http://apxp.info/airports/view/EVRA

where the ILS frequency for this runway is stated as 110.30 - not 108.10 !
After selecting 110.30 in the NAV panel system identified localizer correctly and finally I was able to land with ILS.

Can someone explain to me where is the problem?

Try this, updates the frequencies

 

http://www.aero.sors.fr/navaids3.html

The problem is that the P3d airport navaid database is hopelessly out of date. There is a donationware update for navaids and ILS data here:

http://www.aero.sors.fr/navaids3.html

and a more elaborate payware version, fsaerodata.

Either of these will match up the ILS frequencies to the latest AIRAC release, although I recommend the payware version as it is most complete.

 

It seems that my B739 has up to date frequencies, however the airport itself has the old one. That was my first thought

13 minutes ago, jabloomf1230 said:

The problem is that the P3d airport navaid database is hopelessly out of date. There is a donationware update for navaids and ILS data here:

http://www.aero.sors.fr/navaids3.html

and a more elaborate payware version, fsaerodata.

Either of these will match up the ILS frequencies to the latest AIRAC release, although I recommend the payware version as it is most complete.

 

So is this something different than Navigraph AIRAC data?

The data source is the same. In P3d, the  Navigraph subscription updates only the databases in specific aircraft FMS and GPS units. In XP11, the Navigraph subscription also updates all airports and airspaces. One needs an additional download to accomplish the same data parity between aircraft and the ground in P3d.