A trade hold is a limitation of Steam on sending items from one account to another. While the skin or any other object is in a trade hold, we cannot send it to you. Steam wouldn't allow that.

Usually, trade hold lasts for 7 days, and items become available for sending on the 8th day. However, we are purchasing hundreds of skins every day, so you don't have to wait 7 full days to receive the skin you've got.

If you see an error that the skin you're trying to withdraw is in a trade hold, please, try withdrawing it the next day. Once one of the skin gets released from that limitation, you will be able to send it to your Steam account.