I'm really not a newbie in the cryptoworld and I did countless successful transactions with many different cryptocurrencies.
But a few hours ago I made a big mistake.
(And maybe I get some of the SBDs back, if enough readers find this information valuable.)
I wanted to send some SBDs from the bitshares app to my poloniex account.
As always, I first went to my poloniex account and pressed the deposit SBD button to get the address (which is poloniex) and the correct memo.
But when I tried to send the SBDs from the bishares2 light app, I got the above message telling me, I had to send them to the poloniexwallet account instead.
At that point I should have been warned and cancel the transaction or maybe just send a small amount first, but I didn't.
So I sent all the sweet SBD to the poloniexwallet account at bishares, where they instantly arrived.
I thought, they would be automatically forwarded to my poloniex wallet, cause I used the right memo. But nothing happens. The SBD just sat in that account and are not being forwarded to my poloniex account. They are still there:
As you can see, I was not the only one that sent different currencies to that account. As far as I understand now, it is used to send and receive BTS only.
So I opened up a support ticket at poloniex and hopefully they will send the SBDs back to me. Fingers crossed!
I misunderstood the difference between transfer and withdraw in the bitshares app this time.
What I had to do, would have been going to the "Deposit/Withraw" tab and then use openledger-gateway to withraw my SBDs. Like here:
I also made a post at the bishares-talk forum, which you can read here and 
I found the most helpful hint in his profile over there:
No pain, no gain!
Be careful when you use the bitshares app to move funds:
@shortcut