"We are unable to carry out your instruction. Please contact bank.?

Beneficiaries are usually someone who can receive your ets upon your death or from a trust. Since it is apparently something you can transfer to them to while alive, it must be some sort of trust, but you have provided no details about the type of trust, so we would not know its limitations. So why don't you follow your bank's instructions and contact them to see what the problem is?