Hi, there was some problems some time ago with people booking from other time zones like Australia. Maybe same happens here. Keep also in mind that over the Chrismas and new years period trains may be full and also that only some seats are for Eurail users on Thalys. 

In your case I would try to book via b-europe.com (+4 EUR booking fee): https://www.b-europe.com/EN/Booking/Pass#TravelWish you need a Cover Number of your pass and this you can get it here: 

Exactly what date and time are you trying to make a reservation for? Do you have a 1st or 2nd class pass? How many travellers?

Its not just one train its every train for everytime from paris to amsterdam and amsterdam to london for the next 2 weeks all of them say it isnt working

Can you give an example? I know that many train are sold out.

I can check but I need exact information about what train, date, time, how many travellers and if you have a 1st or 2nd class pass.

Every train from Paris nord to Amsterdam central on the 4/12/22 isn’t working for 2 travellers 

There are no pass holder seats available on the 4th of December from Paris to Amsterdam with Thalys. There is only a limited number of pass holder seats on these trains and the pass holder seats can sell out weeks in advance. There are seats available on the 5th of December. 

On the 6th of December there are more trains available. 

Its not just that route its even from amsterdam to london for the 10th 

If nothing is available from Amsterdam, then check availability from Brussels. Amsterdam - Brussels can be done on the reservation-free intercity train.

If nothing is available for Brussels-Paris, then check Lille - Paris here:

https://travel.b-europe.com/Eurail-GE/en/booking-tgv#TravelWish

Lille can be reached reservation-free via Antwerp.

If nothing is available for Brussels-London, then check the Stena ferry from Hoek van Holland.

But why is none of them working, im looking at paris to anywhere and all of them are unviable its not just the train its travelling anywhere in europe is saying its not working 

Were are you looking on? Eurail.com? or the website I and Anna post here. If you have questions about our reply feel free to ask, we can try to help you (but keep in mind that we are only travellers like you and not Eurail staff). 

The same website for reservations that Anna and I send you for booking Thalys can be used for Reservations on Eurostar services. Check it out. If no trains are on the website, trains are full for Pass Holder. You can avoid this train and check an other route or pay a normal fare ticket for Thalys and Eurostar. 

Reservations for Eurostar and Thalys trains and TGV Brussel-France

Booking reservations for Eurostar and Thalys trains is possible via:

• Interrail.eu/Eurail.com (2€ booking fee per person and train).
• B-Europe website (4€ booking fee per booking, Pass Cover Number needed, request it here), SNCB/NMBS ticket office or by phone
• Thalys Call Centre for Thalys trains by phone (+ 9 EUR booking fee)
• Via French railways ticket office or by phone (press #85 for English, no booking fee, delivery via e-mail).

These reservations are quota-controlled, so you can book only some seats that are for pass users.

• If a Thalys train is not completely full, you can buy a reservation before entering the train at the train manager, also when the pass quota is full. (Passengers on the route Brussel-Collogne tell this possibility. If also other routes are possible not known). 

How to avoid Thalys trains:

• Use reservation free Intercity (direct) Brussel-Antwerp-Rotterdam-Schiphol Airport-Amsterdam. They run hourly.
• Use TGV trains (reservation compulsory) Paris-Lille and from Lille Flanders local trains to Belgium (Antwerp or Brussel with changes in Belgium)

How to avoid Eurostar trains: Use busses via Eurotunnel (not in pass network), or ships from England to mainland Europe (conditions apply).

TGV trains Brussel-France booking possible via:

• Interrail.eu/Eurail.com (2€ booking fee per person and train)
• b-europe website for TGV services Brussel - Marne-la-Vallée/Chessy (Disneyland Paris) and Brussel - Aéroport Charles de Gaulle TGV (Paris CDG Airport) (4€ booking fee per booking, Pass Cover Number needed, request it here) 
• travel.b-europe website for national rides in France (4€ booking fee per booking, Pass Cover Number needed, request it here) 
• SNCB/NMBS ticket office or by phone
• Via French railways ticket office or by phone (press #85 for English, no booking fee, delivery via e-mail).

Eurail is not the best site! Use the sites our experts are suggesting. They are working!! It is most likely the trains are fully booked for passholders

There is no availability from Amsterdam to London on the 10th or 11th of December. The first available train is on the 12th.

Availability Brussels-London looks like this:

As already stated, the Interrail/Eurail reservation website is not the best one. I've only used it once in several dozens of Interrail tours over the past 20 years.
This thread explains other ways to book reservations:

If you want advice on reservations, you need to specify route, date and best also departure time, number of people and 1st/2nd class. The more details, the better the advice you will get.

As for 4/12: I think there are=often the answer to such riddles, again some works along the hi-speed tracks in NL-leading to longer triptimes and reroutings and also trains cancelled/shortened as this has to be due to limited nr of sets. The break via BRU is so well-known and also a money -saver, and even also via the internal SNCF-TGV till LIlle and then onward via Antwerpen-AMS. But these trains also use the notsohi-speed line in NL and may be rerouted then.

(this makes them pass my home close by, except that I am not there right now)

You have to accept that on such lines with all-RES etc passes are not a premium product for low price but only a last resort, like airlines used to have ´if seat available=standby´. IF you want premium-pay for it. Or be creative in using them.

Thanks everyone for the help we had to spend 200 euros on 2 train tickets and now having the same issue as every train from Amsterdam or Brussels to london is saying it can’t be booked and there is no free seat reservations no matter how many change overs so we are back to being Standard

@Ben Mitchell 

2 days ago @rvdborgt gave you information about the availability of pass holder seats between Brussels and London on the 10th of December and the following days. Did you try to make the reservations then?

If you really need to get to London and can't travel with the Eurostar, there are ferries, busses and planes. I'm not an expert on that but there are others in the Community who are. Just ask for help. 

1. As I wrote before: also check from Brussels to London because availability is often much better there. You can do Amsterdam - Brussels reservation-free to connect with Eurostar in Brussels.
2. If you want help, please also mention travel date(s), number of people and 1st/2nd class.

I am still having this problem for tickets I am booking well in advance. I have been trying to make a reservation since the 90 period started for my trip (first train is march 31st) and NOTHING can be booked. i have looked for dozens of different trains and trips and absolutely nothing is able to be reserved.

Please add more details @Sonyah GW  Which exact connection you're trying to book, on which date? On which website? When you like to travel?