Thank you for your answers.
I don't know if the transaction is completed into Gatehub.
I have this :
Sent to Address - 20.0000 XRP a month ago
And I have the same thing for the test of 1 XRP. When I use your tool to check I see my transaction.
So I suppose yes the transaction is mark as completed.
Concerning the balance, on the gatehub wallet yes I have more than 30 XRP.
On the poloiex wallet, I had more than 30 XRP too, because I knew about the minimal XRP on a account.
Concerning the support, yes I opened a ticket to Poloniex when I see that the transfert wasn't completed, but I still haveno feedback.
So do you confirm that the last chance for me is the tweet ?
I don't know how to use it .. ;-)
Thank you for your help.

Hello,
I sent the 2018-01-12 11 AM (French time) 20 XRP from Gatehub to Poloniex deposit but I didn't receive them.
I tried the same on afternoon 2018-01-12 11 5:58PM (French time) with 1 XRP and it works, I receive it on the poloniex deposit.
I wrote to the 2 supports, Gatehub and Poloniex, but no one is answering me.
Could you help me please ? What could I do to in this case ?
Regards,
Marc