DeadLetter not recognised

[martinevent]

I am using the RecoveryStrategy.limitedRedeliver strategy. I want it to send messages to the DLX i declared which is attached to a queue where failed messages are picked off.
I keep getting this
val exx: Exchange[Exchange.Direct.type] = Exchange.direct("op.dead")
val onAbandon: RecoveryStrategy = nack(true)
val redeliverDelay: FiniteDuration = .05.seconds
implicit val recoveryStrategy =
RecoveryStrategy.limitedRedeliver(
retryCount = 1,
exchange = exx,
retryQueueName = retry => "tbd",
onAbandon = onAbandon,
redeliverDelay = redeliverDelay
)
I have it set up as shown above. Is there something I am missing? I do not want a retry queue. I just want it to retry on the same queue, if it fails, I want it sent to the DLX
rabbitmq.client.ShutdownSignalException: channel error; protocol method: #method<channel.close>(reply-code=406, reply-text=PRECONDITION_FAILED - inequivalent arg 'x-dead-letter-exchange' for queue 'tbd' in vhost '/': received none but current is the value 'op.dead' of type 'longstr', class-id=50, method-id=10)