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The amount you sent was too small to pay the bitcoin transaction fee. I happened to notice the transaction had failed, so I just manually refunded it. If you really want to buy bitcoin, I would send 30 SBD or so. If you just want to go to fiat, I would use Litecoin or Ethereum as your intermediate coin instead of bitcoin now. Currently bitcoin transactions cost about $5 USD or more.

Thanks, so one more question please: is $5 the cost per bitcoin transaction (regardless the amount)?

Yes, there is a fixed bitcoin fee per transaction regardless of the amount of the transaction, and the fixed fee is currently about $5 USD. It's why I wrote this post, to warn people about this issue when buying, so they don't pay unnecessary fees.

Thanks! OMG, I wished I knew this a lot sooner.. I have wasted so much transaction fees...

The fees weren't so high in the past, but it's gone up a lot for bitcoin recently.