This is probably the difference between buying the coins on Uphold and withdrawing is less than 24h.
Please wait 24 since last attempt and withdraw then and let us know if all things went fine or not.
As I said, wait 24h and try again.
Please try again, it should work now. If not, please open a ticket, send a screenshot of the error, and we will get this solved formyou ASAP :).