Where are you looking to book ? There are available seat reservations here : https://travel.b-europe.com/Eurail-GE/en/booking-tgv#TravelWish

Be aware that 26th May is the start of a holiday weekend and a lot of people will be travelling. There are no more 10€ limited passholder fares but there are 20€ fares on most trains of that day.

Let me know if it doesn’t work

I tried using above link when i am entering pass number of my eurail global pass its saying invalid number. But its was the same that i  got in email.

Which number are you trying to enter ?

In the email there should be the booking number and the pass number. The pass number worked for me so I don’t know what’s wrong.

Yeah after couple of tries with pass number it finally accepted and able to book the ticket. Thanks a lot bro..

Booked with Eurail Global pass hope it wont be any problem.

Of course it’s fine.

Enjoy your trip !

Thanks a lot brother. You helped  me a lot.