@danieleckler - for services in USA make sure you are adding the ROAMING addon:
"US Roaming - 1 GB Data (10-day) - $20.00"
Regular addons will not work in the USA.
Also, addons only work if your plan is currently in Active status.
Once you successfully add the ROAMING addon to your account the time clock starts counting down=10 days/240 hours these ROAMING adds last.
So, if you want to wait to try tomorrow, it may buy you another day if needed.
When buying an addon, it is a TWO STEP process - be sure to:
1. Add funds to your account, if you don`t have sufficient funds
2. Go back to the Add-Ons page and select your Add-On.
@danieleckler One more thing, All US Roaming has a 10 days 240 hours limit and start counting from the moment you successfully purchased. it actually more advantage for you to leave it at least till tonight to try to buy.
For now, make sure Available Fund has the money and you can try again later