You need to send a photo ID. Providing a credit card is not enough. I've complied. Even though I supplied my credit card I was also required to do the following:
We have received your recent process-credit request. To comply with applicable U.S. financial regulations, Linden Lab is requiring the following information from you to verify your identity. To complete this process and receive your payment, please submit the following:
1. Please attach a colored copy of your government-issued photo ID. The ID must not be expired and must be valid for the next sixty (60) days.
2. If your current residential address does not appear on your photo ID, please provide us with a document that has been mailed to you recently and shows the date, your name and current residential address. Please be sure that this document is dated within the past ninety (90) days. Examples include: Telephone or utility bill, rental agreement, voter registration, insurance statement, bank statement, or any online billing statement
I thought others might like to know. I think it should be in the documentation on selling S$ and processing credit, but I don't see it. I will stand corrected though.
I didn't have much to withdraw, so this was not the reason.
Please also note that this is not a complaint. I sent my photo ID immediately. It is just a heads-up.