When you use the card to RESERVE a hotel room, a rental car, or even to pump gas outside, the merchant sends an authorization request to the issuing bank, same as your credit card. This will act as a debit against your Travelers Card balance until the authorization clears, and it can take up to a week. These authorization "charges" are IN ADDITION to the actual charge. Meaning if you get $20 in gas, but you pay at the pump, there's another $35 sitting there against your funds balance.
So pre-pay for your fuel inside (you may not get a full tank every time, but it's worth it), and PAY for the hotel with the card upon checkout but don't RESERVE or guarantee with it. Otherwise it will be rendered nearly useless on a one-week trip, and AmEx can't help you. It's a merchant thing.
The positive thing is that it's good for several years and only costs $5 for each reload.