You’ll have to give us a clue!

Which route and dates, and where are you?

Arriving in Rome and activating my 3 month global pass on April 18th. Trying to book an overnight train on April 20th to Sicily.  Can’t manage to do it on the app.  Am concerned that if I wait until I arrive on the 18th and try to book it in the train station in Rome the train or seat reservation may well be sold out. So I cannot book my accommodations in Sicily in advance.  

I live in Toronto, Canada

They’re a bit fiddly to book via Interrail. You need to use the website, not the app, and it only allows you to book couchettes if you have a second class pass, even though you would be entitled to buy a sleeper as well. 

https://www.interrail.eu/en/book-reservations#/

I see availability for both couchettes and sleepers on the 20:31 and 23:00 departures on the 18th. €43 for a shared couchette bed, €124 for a private sleeper (if you have a first class pass.)

Also, it’s worth knowing that you can often buy a full ticket (including sleeper) for less than the cost of the supplement you would be paying with a pass. 

Seems like this is true on the 18th. You can get a ticket including private sleeper for €99.90 on the early train, or €83.90 on the later one. No or limited changes and refunds allowed.

Have a look at www.trenitalia.it - you'll need to use Italian place names etc.

Oops. Just re-read that you want to travel on the 20th. In that case, the availability is still there for Interrail reservations, but the separate ticket idea doesn't work - tickets are very expensive for that date.

The recommendation from the experienced travellers in the community is to only make reservations through the Eurail website if no other options are available. Please read more about that below. 

Here is some useful information from the experienced travellers in the Community regarding both planning, reservations and activation of pass and travel days. 

 Planning

The rail planner is normally not up to date, as it only is updated once a month, so to be sure of the time table you better check the timetable and availability on the websites of the national railways. The bigger national railways, like DB (Germany) SBB (Switzerland) and ÖBB (Austria) cover several countries. 

 Reservations